Official Explanation
The best clue in this sentence is its parallel structure. The judge’s keen eye “was surpassed only by the ______ wit with which she castigated them.” Keen means sharply discerning, so look for words that denote a sharpness, or bitingness, of wit. “Mordant” and “trenchant,” both of which are close in meaning to sharp and discerning, are best. Don’t be confused by the other set of synonyms, “assiduous” and “sedulous,” both of which have meanings close to diligent. “Jurisprudent,” which means skilled in the principles of law, is a trap for those thinking about words that might describe a judge. And someone who is “obtuse” would be slow-witted, a word that is the opposite of what the sentence intends.
Answer: B,E