What could be the possible reason for the narrator's mother to use the word "au revoir" in Reading D?(5.0)
A. Since "au revoir" means "goodbye", it doesn't make special sense.
B. His mother preferred French to English.
C. His mother tried to lessen the pain of saying goodbye to a dear family member.
D. "Au revoir" foreshadows a reunion of the narrator and his grandmother later.