- Tue May 29, 2018 6:32 pm
Thanks for the question! This is a difficult question, as it is truly asking us to select the best possible answer; as you note, both answer choices (B) and (C) are talked about in the passages. Let me break down some weaknesses of answer choice (C) and then follow up with why (B) ends up being better.
Answer choice (C) states: a primary purpose of each passage is to "point out possible environmental impacts associated with oil drilling." It is true that the environment is mentioned in both passages. But there are two main weaknesses in this answer. First, and most crucially, no specific environmental impacts are cited by either passage. Passage A points out the difficulty in tracking environmental impacts while Passage B notes that there is environmental concern, but again, neither passage cites specific environmental impacts. Second, while this is harder to quantify, it is fair to say that the amount of time in each passage devoted to the environmental impacts of oil drilling is outweighed by time spent describing the general composition and properties of drilling muds.
And that is what answer (B) says: that a primary purpose of each passage is to "describe the general composition and properties of drilling muds." Both passages spend a lot of time discussing this idea, and so quite simply it is fair to say that this is a primary concern of both passages.
Hope that helps!