CR - In the late 1980s, the population

[jp.jprasanna]

In the late 1980s, the population of sea otters in the North Pacific began to decline. There are two plausible explanations for the decline: predation, possibly by killer whales, or disease. Of these two, disease is the more likely, since a concurrent sharp decline in populations of seals and sea lions is believed to have been caused by disease, and diseases that infect these creatures are likely to be able to infect sea otters also.
Which of the following, if true, most seriously weakens the reasoning?
A. Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey.
B. There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations.
C. Along the Pacific coast of North America in the 1980s, sea otters were absent from many locations where they
had been relatively common in former times.
D. Following the decline in the population of the sea otters, there was an increase in the population of sea urchins,
which are sea otters' main food source.
E. The North Pacific populations of seals and sea lions cover a wider geographic area than does the population of
sea otters.

Why is B wrong? Is it because it is directly countering the evidence given the question, which we should assume to be true??

B. There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations.

excerpt from the question "In the late 1980s, the population of sea otters in the North Pacific began to decline"

Correct Answer is A.

The reason i couldn't select A was as it says "Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey"

The other prey need not be necessarily be "sea otters" in light of this issue option B sounded more appealing and I chose B!

Please help!

[avinashchaturvedi05]

okay, this one is pretty straight forward.There are two possible explanations provided for the decline in the population of creatures. So the most logical way to weaken one( i.e disease) is to strengthen the other( i.e killer whales story).

[jp.jprasanna]

okay, this one is pretty straight forward.There are two possible explanations provided for the decline in the population of creatures. So the most logical way to weaken one( i.e disease) is to strengthen the other( i.e killer whales story).

hey that i get but Why is B wrong? Is it because of the reasons that I have mentioned before?

[avinashchaturvedi05]

I am not too sure , but i think B is wrong because it opposes the facts stated in the question choice.You can not do that, if the question stem says that the population declined - it declined.

Another way to look at is to say that even if the creatures migrated to other locations from north pacific region(or whichever region it is) , the population at north pacific would still decline,isn't it?

[Willy]

In the late 1980s, the population of sea otters in the North Pacific began to decline. There are two plausible explanations for the decline: predation, possibly by killer whales, or disease. Of these two, disease is the more likely, since a concurrent sharp decline in populations of seals and sea lions is believed to have been caused by disease, and diseases that infect these creatures are likely to be able to infect sea otters also.
Which of the following, if true, most seriously weakens the reasoning?
A. Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey.
B. There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations.
C. Along the Pacific coast of North America in the 1980s, sea otters were absent from many locations where they
had been relatively common in former times.
D. Following the decline in the population of the sea otters, there was an increase in the population of sea urchins,
which are sea otters' main food source.
E. The North Pacific populations of seals and sea lions cover a wider geographic area than does the population of
sea otters.

Why is B wrong? Is it because it is directly countering the evidence given the question, which we should assume to be true??

B. There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations.

excerpt from the question "In the late 1980s, the population of sea otters in the North Pacific began to decline"

Correct Answer is A.

The reason i couldn't select A was as it says "Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey"

The other prey need not be necessarily be "sea otters" in light of this issue option B sounded more appealing and I chose B!

Please help!

Let me try my luck with explanation! Choice B says

There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations.

Now, as per your reasoning (and also according to the answer choice B) even if we assume there was no decline in the population of otter because of migration, this reasoning still leaves us with two valid reasons i.e. we still don't know why population of otter declined -- was it due to whale or disease?? But we have to weaken that population decline was not due to disease. But answer choice B leaves us in dilemma.

I also agree with your concern over the usage of "other prey" in answer choice A but only answer choice A is close to valid answer. Sometimes, we have to choose answer choice that is least confusing! :)

In case I am wrong, please correct me.

[jnelson0612]

In the late 1980s, the population of sea otters in the North Pacific began to decline. There are two plausible explanations for the decline: predation, possibly by killer whales, or disease. Of these two, disease is the more likely, since a concurrent sharp decline in populations of seals and sea lions is believed to have been caused by disease, and diseases that infect these creatures are likely to be able to infect sea otters also.
Which of the following, if true, most seriously weakens the reasoning?
A. Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey.
B. There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations.
C. Along the Pacific coast of North America in the 1980s, sea otters were absent from many locations where they
had been relatively common in former times.
D. Following the decline in the population of the sea otters, there was an increase in the population of sea urchins,
which are sea otters' main food source.
E. The North Pacific populations of seals and sea lions cover a wider geographic area than does the population of
sea otters.

Why is B wrong? Is it because it is directly countering the evidence given the question, which we should assume to be true??

B. There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations.

excerpt from the question "In the late 1980s, the population of sea otters in the North Pacific began to decline"

Correct Answer is A.

The reason i couldn't select A was as it says "Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey"

The other prey need not be necessarily be "sea otters" in light of this issue option B sounded more appealing and I chose B!

Please help!

Per forum guidelines, please post the original source and original answers for these questions. I am required to delete threads that do not include original sources. You can see more information about all of this in the forum guidelines here: read-before-you-post-general-verbal-folder-guidelines-t2718.html Thank you!