Answer: The students set up their experiments quickly before the science fair began.
Step-by-step explanation:
In a complex sentence, the subordinate clause and the independent clause are linked by a subordinating conjunction or a relative pronoun. An adverb clause is a subordinate clause that acts as an adverb, and it modifies the verb, an adjective clause, or a different adverb clause.
In this example, only the adverb of time "before" correctly links the provided independent clauses.
"Although" is an adverb of concession, so it doesn´t work in this sentence. "Whenever" is an adverb of time, but doesn´t fit in the sentence provided.