CR Question From GmatClub

[shyamsundar1.g]

Source :Following Question taken from GmatClub.
http://gmatclub.com/forum/some-scientis ... 84425.html
Q:Some scientists believe that 65 million years ago an asteroid struck what is now the Yucatan Peninsula, thereby causing extinction of the dinosaurs. These scientists have established that such a strike could have hurled enough debris into the atmosphere to block sunlight and cool the atmosphere. Without adequate sunlight, food sources for herbivorous dinosaurs would have disappeared, and no dinosaurs could have survived a prolonged period of low temperatures. These same scientists, however, have also established that most debris launched by the asteroid would have settled to the ground within six months, too soon for the plants to disappear or the dinosaurs to freeze.
Which one of the following, if true, most helps to resolve the apparent discrepancy between the scientists’ beliefs and the scientists’ results, as described above?
(A) Loss of the herbivorous dinosaurs would have deprived the carnivorous dinosaurs of their food source.
(B) Dinosaurs inhabited most landmasses on the planet but were not especially abundant in the area of the asteroid strike.
(C) A cloud of debris capable of diminishing sunlight by 20 percent would have cooled the earth’s surface by 7 to 10 degrees Celsius.
(D) The asteroid was at least 9.6 km in diameter, large enough for many dinosaurs to be killed by the strike itself and by subsequent tidal waves.
(E) Dinosaurs were susceptible to fatal respiratory problems cause by contamination of the air by asteroid debris.

Ans : E

I believe the answer is D.Please clarify.Thanks.

[tim]

what's to clarify? why don't you like E? why do you like D?

Before we help with this question, we need you to show some effort of your own. What did you try on this question? Where did you get stuck?

[schmid215]

I don't think this is a particularly well-crafted question, but I can see why E should be the answer. The question speaks of the extinction of dinosaurs, which means their total annihilation. None could be left. Choice D indicates that the asteroid could have caused a tidal wave that would eliminate "many" of the dinosaurs, not all of them. Choice E indicates that "Dinosaurs", meaning all of them, were susceptible to a fatal respiratory infection that would be caused by air contamination of the kind the asteroid brought on. So while D is definitely the second best answer, E is better because it leaves open the possibility of all of the dinosaurs dying.

[tim]

thanks for your analysis!