The infinitive is the most versatile verb form because it can be used as

A. a verb, an adverb, or a conjunction.

B. a verb, a noun, an adverb, or an interjection.

C. a verb, an adjective, or a preposition.

D. a verb, a noun, an adjective, or an adverb.

The infinitive is the most versatile ver form because it can be used as D. a verb, a noun, an adjective, or an adverb.

An infinitive is recognizable because it almost always begin with the word "to" followed by the simple form of the verb. Example: to + sleep.

The infinitive functions as a noun when it is the subject of the sentence or when it is the direct object of the verb in the sentence.

It serves as an adjective when it modifies something.

It serves as an adverb when it explains the reason behind the deed in the sentence.