Which conjunction is a subordinating conjunction?

A subordinating conjunction is a word or phrase that introduces a dependent clause, which cannot stand alone as a complete sentence. The role of a subordinating conjunction is to connect this dependent clause to an independent clause, showing the relationship between the two.

In the context of the given question, "Although" serves as a subordinating conjunction because it introduces a condition or contrast that links the dependent clause to an independent clause. For example, in the sentence "Although it was raining, we went for a walk," the clause "Although it was raining" cannot stand alone as a complete thought, while "we went for a walk" can. The use of "although" indicates that there is a relationship between the two clauses, which is a key feature of subordinating conjunctions.

The other choices listed serve different functions in sentences. "And" and "but" are coordinating conjunctions that connect two independent clauses or similar parts of speech, while "or" functions similarly by providing alternatives. These do not create the dependent relationship characteristic of subordinating conjunctions.