Question

what is the purpose of the underlined part of the sentence? everyone who had seen the performance agreed that the actors had done a terrific job. it is a noun phrase that means the same as everyone. it is a noun clause acting as the object of agreed. it is an adverbial phrase modifying agreed. it is a relative clause modifying everyone.

Explanation:

The under - lined part "who had seen the performance" starts with a relative pronoun "who" and modifies the noun "everyone". A relative clause is a type of dependent clause that starts with a relative pronoun (who, whom, whose, which, that) and gives more information about a noun. Here, it tells us which "everyone" is being referred to - those who had seen the performance.

Answer:

It is a relative clause modifying everyone.