Adverb phrase -

A. a prepositional phrase that modifies a verb, adjective or adverb
B. a prepositional phrase that modified a noun or pronoun
C. a group of words that expresses a complete thought

An adverb phrase is simply a group of two or more words that function as an adverb in a sentence. Just as an adverb can modify a verb, adjective or another adverb, an adverb phrase of more than one word can further describe a verb, adverb, or adjective.

Yes, A is correct.

The correct answer is A. An adverb phrase is a group of words that functions as an adverb and modifies a verb, adjective, or another adverb. It typically begins with a preposition (e.g., in, on, at, for) and is followed by a noun, pronoun, or gerund (a verb form ending in -ing that functions as a noun). Adverb phrases answer questions such as how, when, where, why, or to what extent about the word they modify.

To identify an adverb phrase in a sentence, you can follow these steps:
1. Look for a group of words that begins with a preposition (e.g., in, on, at).
2. Determine if the group of words modifies a verb, adjective, or adverb. Adverb phrases typically describe the manner, place, time, reason, or degree of the verb, adjective, or adverb.
3. Verify that the group of words functions as a single idea and can be replaced by a single adverb.

Remember that an adverb phrase is not a complete thought on its own, so option C is incorrect. Option B describes a prepositional phrase that modifies a noun or pronoun, which is not specific to adverb phrases.