In the given statement, Phineas Barnum appeared, is the adverb clause.
<u>Answer: Option 3</u>
<u>Explanation:
</u>
In the given statement, the exhibition could not begin until Phineas Barnum appeared, the underlined part of the statement represents the adverb clause. The adverb clause is the one where there is a dependent clause, which in real sense, modifies the verb or an adjective or also another verb.
The subject of the statement is, the exhibition could not begin. The conjunction predicate is until. The verb here is the appeared. The verb is being modified and hence it is an adverbial clause.
