Option 1 -> Jocular means humorous and playful, which is similar in meaning to jovial, not opposite.
Option 2 -> Crestfallen means sad, disappointed, or dejected, which is the opposite of jovial (cheerful and friendly).
Option 3 -> Convivial (likely misspelled) means friendly and lively, similar to jovial, not opposite.
Option 4 -> Gaily means in a cheerful manner, which aligns with jovial rather than opposes it.
Hence, Option 2: Crestfallen -> Jovial describes someone cheerful and good-spirited, while crestfallen describes someone sad and downcast, making them perfect antonyms -> correct