Answer:
A. Dr. Hernandez left with a spring in his step.
Step-by-step explanation:
An adverbial phrase is known to be a group of words which actually function as an adverb. It helps to modify verbs, adverbs, adjectives, sentences, etc.
Option A is an adverbial phrase because it tells about the manner in which Dr. Hernandez left. It is an adverbial phrase of manner.
Adverbial phrase of manner actually states how something is done or carried out.
Therefore, Option A is the correct answer.