Hi AZ,
For this question (and many other questions) you'll find your speed improves a lot with a good prephrase. Must Be True questions are often overlooked questions for prephrasing because they don't always have that natural argument to help/hurt/analyze. But that doesn't mean we can't predict what we expect to see and work with the facts that we have. And we should!
I always start by reading through a stimulus and trying to make connections as I go. In this one, I read through the whole stimulus, then worked my way back from the end. We know that Lee's novel passed with flying colors. The novel was about San Francisco. We do know based on this stimulus that Lee must know it at least as well as the reviewer in order for Lee's book to pass the test. Passing the test means that the review can trust the storyteller and the tale.
In this case, since there are so many conditionals, I may draw out a chain.
Take writer seriously
Writer knows city at least as well as I do
Trust storyteller
Increase enjoyment
The chain should keep me from making any mistaken reversals/negations as I work though the answer choices.
Let's look at the choices you considered. The big problem with answer choice (A) is that the stimulus only says that his enjoyment is increased if it is a GOOD book that he trusts. Not virtually any book, but a good book. It's true that the stimulus talks about "good books" but the answer choice says virtually any novel, so we aren't limited to only good books here. That's way too broad, and we can knock it out.
Answer choice (B) tries to use a mistaken reversal from trusting the storyteller to the writer knowing the city well. We can eliminate this one quickly. We don't need to analyze it very long once we see it's a mistaken reversal.
Answer choice (D) can be crossed off because we don't have this knowledge. We only know about books that take place in cities the reviewer DOES know well. We can't try to draw a must be true based on books that take place in other cities. Without information in the stimulus we can point to that supports the conclusion, it's wrong.
Answer choice (E) is correct---we must know that Lee knows San Francisco at least as well as the reviewer for it to pass the test.
It sounds like you are doing a good job analyzing your answer choices, but you aren't feeling confident moving eliminating the choices. Feel confident in your analysis, and move quickly. Once an answer choice is wrong for any reason, it's wrong.
Hope that helps!
Rachael