Try reading book reviews from the New York Review of Books. Not only are they about lit, but they're also in the form of an argument so it's a win win.
The stimulus states: "the resulting *lack of substance* leads to books
that are *short-lived items*" - This directly supports (B)s notion that: "The substance of a children's book is important to its longevity."
Check out the website for the trainer (www.thelsattrainer.com) - the author has study schedules that should give you a good idea of how long it should typically take to go through the book.