Hi Vivian! Happy to help you out with this
The question is asking us about the attitude itself that is mentioned in lines 5-9. To understand what the question is asking, we need to go back to the passage and see what the "familiar" attitude is. According to the passage, the "familiar" attitude is that enjoyable novels are "slightly lowbrow" and true literature is "a tiny bit dull." The confusing aspect of this question is that lines 5-9 refer to this as a "familiar, false opposition." However, the word "false" just refers to the author's attitude towards this "familiar opposition" rather than showing that there are two different positions. The question is asking us about the "familiar opposition" itself, rather than the author's attitude towards it.
So the correct answer choice does not need to represent two separate views, but rather, it needs to represent this idea that enjoyable novels are "lowbrow" and true literature is "dull." Answer choice (C) captures the idea that true literature must be "dull" by saying that these works place demands on their readers rather than "divert them." In this context, "divert them" means that true literature should not amuse its readers. If true literature should not amuse its readers, then this captures the idea in lines 5-9 that true literature must be "a tiny bit dull."
Answer choice (D), on the other hand, does not discuss the idea of novels being dull vs. enjoyable and using this as a metric for whether they are true literature, instead discussing the idea of popularity. Since popularity of the novels was not discussed in the "familiar" attitude described in lines 5-9, this answer choice is incorrect.
To sum up and answer your question about avoiding falling into grammatical traps:
The tricky part about this question is realizing that the "familiar" attitude references the opposition of enjoyable novels as "lowbrow" and true literature as "dull." Although lines 5-9 state that this is a "familiar, false opposition," the important thing to keep in mind is what "false" is referring to, which is the author's view on this "familiar opposition." Since the question does not ask about the author's attitude but instead about the claim itself, we need to find an answer choice that captures the view of the "familiar" attitude, rather than two views.
If you're ever stuck on what a question is referring to/what a question is really asking, sometimes it is best to flag the question and come back with a fresh set of eyes once you've finished the rest of the section; when you come back to the question, you may realized how you were misinterpreting it.
I hope this helps, and please let me know if you have any other questions!