Answer:
The correct option is D. adjective phrase.
Step-by-step explanation:
The adjective phrase also knows as adjectival phrase, refers to a group of words which describe a noun or pronoun in a sentence. The first word of such adjectival phrase is usually an adverb or a preposition.
Bearing all this in mind, it could be said that the phrase in bold in the sentence "Tomorrow, the mayor will announce her plans FOR THE NEW COMMITTEE." correspond to D. adjective phrase.