正确答案:BC
解析：
This is a tough question because so many of the answer choices seem to work. Remember though, we are looking for a pair of similar words. Therefore we can get rid of (A) and (D). (E) and (F) are tempting, and they are similar words.

To say that someone pulled off an obvious crime sounds a bit absurd. Also, it suggests that the person isn't too bright. The suspect is very crafty. Notice the clues, "...a display of cravenness..." He is pretending to be the opposite of how he behaved during the crimes, i.e., (B) and (C).