Answer:
A: In the selected sentence, the word gardening is a gerund, and the gerund phrase functions as the subject.
Step-by-step explanation:
The gerund is the ing form of the verb : it has the same form as the present participle: verb + ing. A gerund is a noun and it can have the role of a subject of a sentence , a complement of a verb, or can come after some verbs, or prepositions. In this sentence is used as the subject, and the rest of the sentence is the predicate, the description of the subject