Answer: C) Billy and ____walk to school each morning.
Explanation: the nominative case in a sentence is a grammatical case for when nouns or pronouns are the subject of a verb. The nominative pronouns are I, you, he, she, it, we and they. In the given sentences, the one that is missing a nominative pronoun is option C, it should say "Billy and (nominative pronoun) walk to school each morning" for example, it could be: "Billy and I walk to school each morning"
The use of the understatement in the excerpt that affects this part of the scene is that he or she has to say something that is less important than it already is. He or she tried to restrain himself or herself to escape the effect it has.
C. It heightens how ridiculous it is that two women think they are engaged to the same man.