Try to think of a disagreement or agreement you've EVER had with a family member. Even if you are exaggeration or making a bit of it up I believe it to be fine. Write about something simple like disagreement over the last cookie or bed time.
Be worried and ask where I have a been.
"To write a novel", is the subject in the infinitive phrase.
His ultimate goal is to write a novel. So, "To write a novel" functions as a noun in the sentence. Hence, the answer is A. Noun.
