Final answer:
The appropriate pronoun to fill in the blank in the dialogue is 'vous'.
Step-by-step explanation:
The appropriate pronoun to fill in the blank in the dialogue is B. vous. The pronoun 'vous' is the second person plural pronoun in French and is used when addressing more than one person or when showing respect to a single person. It is the equivalent of 'you' in English when addressing a group of people or someone formally.
Learn more about Pronouns in French