Question

what is the grammatical function of the gerund?
in baseball, bunting can be a good strategy to help runners advance to the next base. when the batter hits the ball softly, the infielders are forced to run in toward home plate.
it is a subject.
it is an object of a verb.
it is an object of a preposition.

Explanation:

In the sentence "In baseball, bunting can be a good strategy to help runners advance to the next base", the gerund "bunting" is performing the action (the action of bunting is what is being discussed as a strategy). A subject is what performs the action in a sentence. An object of a verb would be the receiver of the action of a verb (e.g., "I like reading" - "reading" is the object of the verb "like"). An object of a preposition would follow a preposition (e.g., "He is good at singing" - "singing" is the object of the preposition "at"). Here, "bunting" is not following a verb or a preposition in the sense of being their object, but is the doer (in a general sense for the action described by the verb "can be") in the sentence.

Answer:

It is a subject.