Question

when the subject of a sentence performs the action in the sentence, the verb in the sentence is in the active voice

Explanation:

The question is about sentence structure, specifically the concept of active voice in grammar. In active voice, the subject of the sentence is the doer of the action (performs the action of the verb). This falls under the subfield of Linguistics (within Arts) as it deals with language structure and grammar.

Answer:

When the subject of a sentence performs the action in the sentence, the verb in the sentence is in the active voice. So the correct completion (based on the context of the question, likely to confirm that the verb is in active voice here) is that the verb is in the active voice. If this was a fill - in - the - blank or a confirmation question, the answer relates to identifying the active voice situation where the subject acts.