Did anyone else get thrown off by the fact it says "explanations" in D when really it seems the author is arguing for one explanation (the cause being synthetic pollutants)?

Can someone explain in more detail why 24 is D and not E? I debated between the two a lot but chose E. I picked E because the passage describes how the agents would go to the gossip columnists and thought of E as more of a literal answer, while D is more big picture description.

Is it ok that this author does not ever directly cite or acknowledge any perspectives? I know the earlier page on this says you can paraphrase, cite or say things like "opponents of this view....".