A favored theory to explain the extinction of dinosaurs, together with many other species, has been the globally catastrophic collision of a large asteroid with the Earth. Supporting evidence is an extraterrestrial chemical element in a layer of dust found worldwide at a geological level laid down contemporaneously with the supported event. A new competing theory contends that any asteroid impact was irrelevant, because it was massive volcanic activity that caused the extinctions by putting enough dust into the atmosphere to cool the planet. The Deccan region of India contains extensive volcanic flows that occurred within the same time period as the supposed asteroid impact and the extinctions.
Logical Chain:A causes C ( Asteroids depleted dinosaurs)
No, B causes C (Volcano depleted dinosaurs
In order for this chain to whole true, A must have not caused B to happen and vice and versa.
The new theory assumes that
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(A) the massive volcanic activity was not caused by the impact of an asteroid
A was not caused by B. This matches our thought. Keep it.
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(B) no individual dinosaurs survived the impact of the asteroid, if it occurred
This does not explain whether Volcano killed the dinosaurs. (B) is out.
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(C) the extinctions took place over a longer time period than they would have if caused by the impact of an asteroid
Duration is irrelevant. We only need to know which one was the cause.
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(D) other volcanic eruptions were not occurring at the same time as those in the Decean region
Other volcanic eruptions are irrelevant. The reasoning is only concerned with 1 massive volcano.
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(E) it is not possible to determine which would have occurred first, the volcanic flows in the Decean region or the supposed impact of an asteroid
If both can't be determined so how did the author come to the conclusion? Non-sense. (E) is out
A is left. A is the answer.
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