There are no pivots in this sentence, so you simply need a word that fits the description of a book that explores the “many ways in which 19th - century women writers....” In other words, you can just fill in the blank with“explore.” Note that “interrogate" is being used in a figurative sense here (i.e., it's not referring to a literal interrogation, as of a criminal), though the goal of both types of interrogation is to pry deeply into an issue. Debunk and explode are an incorrect pair, meaning “disprove.” Interpolate (insert between parts, pieces, or things) and castigate (criticize or punish severely) have no relationship. Castigate almost fits into a triple with the incorrect pair, but it's more of a criticism than an attempt to disprove something.