Which of the following is NOT a coordinating conjunction?

The term "coordinating conjunction" refers to words that connect words, phrases, or clauses that are similar or equal in structure. Common coordinating conjunctions include "for," "and," "nor," "but," "or," and "yet."

In this question, "although" is identified as the choice that is not a coordinating conjunction. Instead, "although" is a subordinating conjunction, which means it is used to connect a dependent clause to an independent clause, indicating a relationship that often implies contrast or condition. For example, in the sentence "Although it was raining, we went for a walk," "although" introduces the dependent clause "Although it was raining" and connects it to the main idea of the sentence.

The other choices—"for," "and," and "but"—are all functions of coordinating conjunctions that link similar syntactic elements. Therefore, understanding the distinction between coordinating and subordinating conjunctions is crucial in identifying the role each word plays in sentence structure.