We know many scientists believe that air pollution enhanced the strength of El Nino. But we don’t know that this belief is true. So we cannot infer (A).

We know that fires were unusually large and intense due to the unusually strong El Nino. This doesn’t imply that if the El Nino weren’t as strong, there would only be “few” large/intense forest fires. Perhaps there would not be as many, or the fires would be less large/intense; this doesn’t imply there would only be “few,” however.

We only have evidence concerning large/intense fires in a single year — 1997. This doesn’t support a claim about what is “generally” the case concerning forest fires during a strong El Nino.

We know that some scientists believe air pollution contributed to the strength of El Nino in 1997. But we’re not told anything about what scientists believe concerning the fires. So we can’t infer that scientists hold a belief about the fires.

We know that the strength of El Nino in 1997 caused a drought. So, if air pollution strengthened the El Nino, that implies that air pollution also played a causal role in the drought. Note that (E) doesn’t assert that air pollution in fact strengthened El Nino; it merely asserts what would be true IF air pollution strengthened El Nino.