The second half of the second paragraph discusses P.D. James's critics. "Others find her pretentious and tiresome; an inverted snobbery accuses her of abandoning the time-honored conventions of the detective genre in favor of a high-brow literary style. (17-20)." So, we are saying that critics think James's writing is too snobby, which is different from being too confusing or convoluted.
To expound on this thought, the author brings forth the examples of Waugh and Oakes. Waugh wants James to "get on with it," insinuating that James is taking too long to get to the crux of the detective/crime novel. Oakes mirrors this sentiment asking why we cannot hurry up and slap handcuffs on the killer already.
So, it is not that her writing is convoluted, i.e. Answer choice (E), but that she spends too much time focusing on things that are not essential to the crime plot, i.e. answer choice (A): "too much material that is extraneous to the solution of the crime."
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