Explanation

The clue here is that the investor’s mood seemed incongruous in light of the bad news about the stock market; since incongruous means out of place, you need a word like happy for the blank. Both inconsolable and funereal are nearly the opposite of what you’re looking for, so eliminate choices (C) and (E).

Neither enervated, which means weakened, nor sardonic, which means mocking and derisive, is supported by the sentence, so eliminate choices (A) and (D).
Both sanguine and buoyant can mean happy, so choices (B) and (F) give you appropriate, equivalent sentences.