Which of the following types of words can express a complete thought when used in a sentence?

The reason why the choice indicating verbs is suitable is that verbs are essential components of a sentence that signify action, occurrence, or a state of being. A complete thought often requires a subject and a verb to form a sentence. For instance, the sentence "She runs" conveys a complete idea due to the combination of the subject (she) and the action (runs).

While nouns play a crucial role in sentences by representing people, places, things, or ideas, they typically do not express a complete thought on their own without the presence of a verb. Similarly, conjunctions are used to connect words, phrases, or clauses, but by themselves cannot express a complete thought without additional context.

Therefore, while verbs are essential to forming complete thoughts, nouns and conjunctions generally require more context or structure to do so effectively.