Which of the following defines verb mood?

Choices
the fact or opinion that is addressed by the use of a verb.
the purpose of a sentence, expressed through the verb.
the use of auxiliary, or helping verbs, in sentences.
the manner in which the verb expresses an idea in a sentence.

I chose the manner in which the verb expresses an idea in a sentence.

This is correct! Verb mood refers to the way in which a verb expresses the speaker's attitude towards a particular situation or action. Common verb moods include indicative (stating a fact or asking a question), imperative (giving a command or request), subjunctive (expressing a hypothetical or uncertain situation), and conditional (expressing a hypothetical or uncertain situation dependent on a certain condition).