Why D?

This is a Paradox question so we are looking for the answer choice that serves as a possible explanation to the discrepancy in the stimulus. What is the discrepancy? Adding dried grass clippings to garden soil results in better than average plant growth but fresh grass clippings causes poorer than average plant growth. Let's take a look at (D), "Fresh grass clippings mixed into soil decompose rapidly, generating high levels of heat that kill beneficial soil bacteria." Notice that this serves as a possible explanation for the discrepancy set forth in the stimulus so (D) would be the correct answer. You are correct re: (B) and (C). They do not provide a reason for the difference set forth in the stimulus. Hope that helps! Please let us know if you have any other questions.

I'm having a difficult time seeing the difference you're identifying between B and D. Could you please elaborate on the reason why B specifically is not answering the reasoning/difference in the stimulus?

@Jwebb, The stimulus tells us that dried clippings -> beneficial soil bacteria -> better plant growth, whereas fresh clippings -> poor plant growth. How do we explain the difference? The correct answer (D) tells us that fresh clippings kill beneficial bacteria that contributes to better plant growth - fresh clippings -> kill bacteria -> poor plant growth. Since the stimulus tells us that bacteria contributes to better plant growth, thus answer choice is consistent with the stimulus and explains the impact of fresh clippings on plant growth. The issue with (B) is that it only strengthens the part of the argument telling us that dried clippings result in better plant growth as nutrients released by clippings are immediately available to beneficial bacteria, but it fails to provide any additional information explaining why fresh clippings result in poor plant growth. It might be tempting to infer that fresh clippings release nutrients at a slower pace, but this is an unwarranted inference. Since (B) fails to explain the disparate impact of fresh versus dried clippings, we can eliminate this answer choice. Let me know if you have any further questions.

Cooki mlol

I'm sorry my phone was open and I accidentally typed something. My bad.