Is the following underlined group of words an adverb clause or an adverb phrase? "I usually go to my grandmother's house on my birthday."

Responses
A adverb clauseadverb clause
B adverb phrase

B adverb phrase

The underlined group of words "on my birthday" acts as an adverbial phrase, modifying the verb "go" by specifying when the action usually takes place. Adverb clauses, on the other hand, contain a subject and a verb, but this group of words does not.