OE
The “nevertheless” that precedes the blank indicates that the book’s accessibility contrasts in some way to its scientifc insights and demanding subject matter. Among the choices for the blanks, there are two pairings that would yield similar meanings: “experts/authorities” and “nonspecialists/laypersons.” Considering these two pairings, it would not be surprising if a book rich in scientifc insights were accessible to experts, whereas writing such a book accessible to those not in the feld would be a feat. “Nonspecialists/laypersons,” then, provides the necessary contrast to the book’s other qualities, so it is the correct response. The other two choices, “skeptics” and “zealots,” can be eliminated straightaway because neither has a synonym among the other responses; in addition, neither helps form the contrast that the use of “nevertheless” requires.
Thus the correct answer is nonspecialists (Choice C) and laypersons (Choice F).