Which sentence contains an adverb modifying an adjective the barn cat heard happily the very content CAL Jude could unfortunately it began to rain slowly the sleepy pig rolled over

The barn cat heard happily as the very content CAL Jude could unfortunately it began to rain slowly.

The sentence "The barn cat heard happily" contains an adverb modifying an adjective.

The sentence that contains an adverb modifying an adjective is "The barn cat heard happily."