What part of speech does the word in parentheses represent in the sentence: "He was a great tennis player (but) he lacked commitment?"

The word "but" in the sentence serves as a conjunction, which is a part of speech that connects clauses or sentences. In this context, it links the two independent clauses "He was a great tennis player" and "he lacked commitment." The conjunction "but" indicates a contrast between the two statements, suggesting that despite being a talented player, there is a limitation in his commitment.

Understanding the role of conjunctions is essential because they are key in structuring sentences and conveying relationships between ideas. Other options like adverb, preposition, and adjective refer to different functions that do not apply in this scenario. Adverbs modify verbs, adjectives, or other adverbs, prepositions link nouns to other words in a sentence, and adjectives describe or modify nouns. Therefore, recognizing "but" as a conjunction clarifies its purpose in the structure of the sentence and enhances comprehension of how ideas are connected within the text.