Final answer:
The question is about the first use of interludes interspersed with pantomime accompanied by music in theater.
Step-by-step explanation:
The subject of this question is Arts. The question asks about the first use of a specific practice in theater, which is interludes interspersed with pantomime accompanied by music. This practice was first used by Agathon, a playwright, to describe a monologue he had written. The question is related to the history and development of theater as an art form.