Quite a difficult question. In this question, we are tasked with identifying the logical force of the critic's argument.
In predicting this answer, I would think that the logical force of the critic's argument is quite weak. Simply because study showed that some well managed farms have not decreased yields while cutting back on those undesirable antibiotics, pesticides, etc. Therefore, what point is the critic making by saying that not all farms will be able to do so and that the study cherry picked the farms that likely could? None. The study never said all or most can, only that some. The only way the critic could prove with any force that the study is incorrect is by proving that no farms can do so.
Answer choice D is going after this point. Even if the critics did prove that it was not suitable for the majority of farms (which they didn't), this doesn't properly evaluate the logical force of their argument, which is no force. Irrelevant argument!
Please let me know if you have any other questions and if this helped!