Notice that this is a cause and effect stimulus. The observed effect we are trying to explain is the extinction of the dinosaurs and we are presented with two different theories, or proposed causes, i.e. the asteroid-impact theory and the volcanic-activity theory.
The question stem asks us to weaken the asteroid-impact theory that has been used to explain the extinction of the dinosaurs.
Let's take a look at the answer choices:
(A) is incorrect because it is completely irrelevant. Whether or not dinosaurs congregated in large groups during some part of their lives does not indicate that the asteroid-impact theory is at least incomplete if not false.
(B) is incorrect because again it is completely irrelevant. The asteroid-impact theory puts forth the globally catastrophic collision of a large asteroid with the Earth as the cause for the extinction of the dinosaurs, so the ability to escape the local effects of certain catastrophes does nothing to this theory.
(C) is incorrect because we are not debating whether or not the dinosaurs actually went extinct. We are trying to weaken one of the theories as to why the dinosaurs went extinct.
(D) is incorrect because again it is completely irrelevant. The climate when the dinosaurs were alive does nothing to the asteroid-impact theory.
(E) is CORRECT because it weakens the cause-and-effect argument of the asteroid-impact theory, i.e. a globally catastrophic collision of a large asteroid with the Earth caused the dinosaurs to go extinct, by showing the proposed cause (asteroid impact and the layer of extraterrestrial dust) without the observed effect (i.e. dinosaurs were not extinct after the impact as demonstrated by the fact that dinosaurs still existed after the impact, decreased from 13 to 5).
Hope this helps! Please let us know if you have any other questions.
Julie-VJuly 16, 2019
I'm not sure if I follow the logic behind E's explanation. So the discovery of dinosaur teeth above the dust layer is what disproves that the asteroid impact theory is false? Is evidence of dinosaur remains above the dust layer contradictory against the theory that assumes the dust layer would have been above all dinosaur remains?
