Choose the sentence that is grammatically correct.

The sentence "The rain has poured heavily" is grammatically correct because it uses the present perfect tense, which is appropriate for describing an action that occurred at an unspecified time in the past and has relevance to the present moment. The subject "the rain" is singular, and thus the singular verb "has" correctly aligns with the subject. Additionally, "poured" is the past participle form of the verb that pairs with "has," and "heavily" is the appropriate adverb modifying how the rain poured.

This choice accurately reflects correct subject-verb agreement and tense usage, showcasing a complete action relevant to the present context.