CR - Assumption - Researchers studying the spread of the

[ehsu]

Researchers studying the spread of the Black Plague in sixteenth-century England claim that certain people survived the epidemic because they carried a genetic mutation, known as Delta-32, that is known to prevent the bacteria that causes the Plague from overtaking the immune system. To support this hypothesis, the researchers tested the direct descendants of the residents of an English town where an unusually large proportion of people survived the Plague. More than half of these descendants tested positive for the mutation Delta-32, a figure nearly three times higher than that found in other locations.

The researchers' hypothesis is based on which of the following assumptions?

(A) Delta-32 does not prevent a carrier from contracting any disease other than the Plague.
(B) The Plague is not similar to other diseases caused by bacteria.
(C) Delta-32 did not exist in its current form until the sixteenth century.
(D) No one who tested positive for Delta-32 has ever contracted a disease caused by bacteria.
(E) The Plague does not cause genetic mutations such as Delta-32.

I was between D and E and ultimately chose D. Is D incorrect because it's simply restating the author's conclusion? That Delta-32 prevents the disease from happening? How does E work? If I use the negation technique for E, I'm saying, the Plague does cause genetic mutations such as Delta-32, therefore the author's conclusion is negated. But for D if I also use the negation technique, that people who tested positive for Delta-32 HAS contracted a disease caused by the bacteria, then doesn't that destroy the conclusion as well? In that Delta-32 doesn't prevent the plague from overtaking their bodies because they contracted the disease.

I just need a more thorough explanation than the one provided in the CAT exam as assumption questions are my weakness. Thank you!

[rahulsh555]

Hi Let me try to explain.
Let A =The Plague does not cause genetic mutations such as Delta-32.
Negation of A : The plague causes genetic mutation such as Delta32.

Hypothesis :They carried a genetic mutation, known as Delta-32, that is known to prevent the bacteria
that causes the Plague from overtaking the immune system

It says Delta 32 was already there and that only prevented the immune system.

But you negation of A says Plague only caused the Delta32 and it completed invalidated the hypothesis. Hence this is the answer.

B =No one who tested positive for Delta-32 has ever contracted a disease caused by bacteria.

Negation of B= All who tested positive for Delta-32 has ever contracted a disease caused by bacteria.
It never invalidates the Hypothesis.

Hope I answer your question.

[jlucero]

Hi Let me try to explain.
Let A =The Plague does not cause genetic mutations such as Delta-32.
Negation of A : The plague causes genetic mutation such as Delta32.

Hypothesis :They carried a genetic mutation, known as Delta-32, that is known to prevent the bacteria
that causes the Plague from overtaking the immune system

It says Delta 32 was already there and that only prevented the immune system.

But you negation of A says Plague only caused the Delta32 and it completed invalidated the hypothesis. Hence this is the answer.

B =No one who tested positive for Delta-32 has ever contracted a disease caused by bacteria.

Negation of B= All who tested positive for Delta-32 has ever contracted a disease caused by bacteria.
It never invalidates the Hypothesis.

Hope I answer your question.

Great explanation with one small correction- the opposite of "no one" is not "all", but rather "at least one":

B =No one who tested positive for Delta-32 has ever contracted a disease caused by bacteria.

Negation of B= At least one person who tested positive for Delta-32 has ever contracted a disease caused by bacteria.

[RishavR393]

What is the problem with option B here,

A = The Plague is not similar to other diseases caused by bacteria.
If we negate A, we get The Plague is similar to diseases causes by bacteria.
This would break our conclusion as D32 cannot help much to stop spreading of plague?

[Sage Pearce-Higgins]

Good job for negating the answer choice to see if it's a real assumption, but take the negated version of B again: "The Plague is similar to diseases causes by bacteria." This doesn't undermine our conclusion that "certain people survived the epidemic because they carried a genetic mutation, known as Delta-32, that is known to prevent the bacteria that causes the Plague from overtaking the immune system". Sure, the Delta-32 mutation could protect from other diseases, but that doesn't stop it protecting from the Plague too.