The first thing you should notice is the structural road sign “regardless,” which functions as a detour road sign. Therefore, the clause after the semicolon will depart from the meaning of the first clause. You’re told in the first clause that Cora is “not known for her reticence,” so the second will indicate hesitance or reluctance. The blank will be an adverb that describes “acquiesced,” which means to “give in” or “relent.” Since you’re looking for a word that shows Cora being uncharacteristically reticent, a good prediction is reluctantly. Evaluating the answer choices, you can immediately reject (A) jejunely, “childishly,” which doesn’t make sense, and (B) exuberantly, “gleefully,” which implies Cora was anything but reluctant to speak at the conference. You can eliminate (C) willfully, since it implies that she was headstrong, which does not harmonize with reluctantly. Choice (E) candidly, “openly,” doesn’t have a meaning close to reluctantly. That leaves (D) grudgingly, meaning “resentfully unwilling,” and (F) timidly, which means “in an easily frightened way.” These two are the best matches.