Whenever the passage describes a cause-and-effect relationship, it helps to highlight the cause and the effects. These relationships almost always help to answer at least one question.
We learn about the effects of El Nino in lines 22-26. The effects we might want to highlight are (1) “warms sea surface,” (2) “warms atmosphere,” (3) “mask cooling brought by an eruption,” and (4) “mimic volcanic cooling” if the warming effect is beginning to fade.
(A) is wrong because of (1). (B) is wrong because of (3). (C) is wrong because of (2) + our knowledge that El Nino is a “cyclical weather phenomenon” (lines 19-20). (E) is wrong because of the third paragraph.
(D) is correct because “feedback loops” are discussed in the fourth paragraph, and that paragraph doesn’t assert or imply a connection to El Nino.
