Answer: A. The hopeful actors agreed to meet in the dressing room before the audition.
Explanation: An adverb phrase is simply a phrase that acts as an adverb to describe a verb, adverb, or adjective. Adverb phrases typically answer the questions how, where, why or when something was done. From the given options, the sentence that contains an adverbial phrase is the corresponding to option A: The hopeful actors agreed to meet in the dressing room before the audition, the adverbial phrase "before the audition" answer the question "when."
