Which group of words is NOT a phrase A. Leaving the dog behind B. Because she smiled at me C. Smashing into a fence D. Before the first test E. Pushing the sofa

B. Because she smiled at me.

Explanation:

Phrase is a group of words which forms a unit in a sentence.

Phrases are classified into noun phrase, verb phrase, adjective phrase, gerund phrase, infinitive phrase.

In the following sentence: the lost dog was found by the police.

The lost dog is a noun phrase

Was lost is a verb phrase

By the police is a prepositional phrase.

Option B is not a phrase, rather it is a clause because it has connector, subject and verb.