HURRY WILL GIVE BRAINLIEST!!!!!

Determine whether the underlined portion of the sentence opener below is an adjective, adverb, infinitive, or prepositional phrase.

Humming softly "to herself", the trainer fed the elephants.


Please select the best answer from the choices provided.

A.

adjective

B.

adverb

C.

infinitive

D.

prepositional phrase