Hi, If we analyze the structure of the passage we can figure out that they: 1) introduce a phenomenon (more species in the tropics - middle latitudes). 2) propose three hypotheses which they end up rejecting (time theory, species-energy hypothesis, climatic stability) 3) introduce and defend a fourth hypothesis, the rate-of-speciation hypothesis.
A) The passage disagrees with this, they like the rate-of-speciation hypothesis. B) True, but this isn't the main point, we're trying to figure out why this is the case. C) This gets at the structure and the main point - we considered multiple theories and then landed on one which the author supports! D) Not the main point, we're evaluating the hypotheses. E) While this is an issue for one of the hypotheses, it definitely isn't the main point of the passage and it doesn't even apply to all of the hypotheses.
