Which description is accurate and true of all three sentences?
1. We struggled to understand the complicated algebraic expressions.
2. We could not wait to hear our grades on the final exam.
3. We failed to demonstrate our knowledge and understanding.

A) All sentences have a gerund that takes the place of a verb.
B) All sentences have a participle that replaces a verb phrase.
C) All sentences have an infinitive that takes the place of a noun.
D) All sentences have a participle phrase that functions as an adjective.