(A) is wrong because there's no evidence for it. Indeed, it's a "fundamental tenet" of geophysics that Earth's magnetic field can exist in either of two polarity states, suggesting that all geophysicists believe this. While there may be some dissenters, it's not something that we can conclude based on information in the passage.
(C) is wrong because there's no information given to us about the relative speed of polarity reversal between the two theories.
(D) is wrong because we weren't told when the heat-transfer hypothesis was introduced, nor that geophysicists' understanding increased significantly.
(E) is wrong because although it would be in line with the asteroid-impact hypothesis, this hypothesis is only presented as one of multiple theories, and one that "more controversial" at that. Thus, we can't conclude anything about the polarity of Earth's magnetic field from the theory. Hope this helps!
RynNovember 26, 2021
So E is wrong because this is one of many theories. I am confused. Can you tell us exactly how it is not supported, please? Are you trying to say we can't conclude anything from theories?
jakennedyJanuary 19, 2022
Hi @Ryn,
It is not that we can never trust a theory. The key is to look out for the logical force. If the author indicated that they agree with a particular theory and provided strong support to suggest that the theory is true, then it could have been the correct answer choice. In this case, however, the author is listing off multiple theories and has not stated that one of them is correct. To make matters worse, in lines 59-the end of the passage, it says, “theories that depend on extraterrestrial intervention seem less convincing than theories like the first (heat-transfer theory). So the author does not even agree with the asteroid-impact hypothesis.
Takeaway: On RC passages, what the author thinks is king.
