Which of the following is an example of a subordinating conjunction?

A subordinating conjunction is used to connect an independent clause with a dependent clause, helping to indicate a relationship such as cause, time, or condition. "Because" is a perfect example of this type of conjunction, as it introduces a subordinate clause that provides a reason for something mentioned in the main clause. For instance, in the sentence "I stayed home because it was raining," "because" connects the reason for staying home to the main assertion.

In contrast, the other options function as coordinating conjunctions, which link similar elements of equal grammatical rank, such as two independent clauses or phrases. "And" and "but" are commonly used to connect two grammatically equal components or ideas, while "for" is often used to provide a reason but does not subordinate the clause that follows it. This distinction is essential for understanding how different conjunctions function within sentences.