Verified Answer :

Infinitive
phrases starts with infinitives that is, “to” added by a simple verb and can be
used as nouns, adjectives or adverbs. In the case of including a main clause in
the sentence, infinitive phrase separates it with comma.

In
the sentence:

Jane
wanted to forget about the matter.

The
infinitive phrase is ‘to forget about the matter’ and it is used as an adverb.

The correct answer is a noun.