Final answer:
The correct form of the verb 'llenar' is 'llene'.
Step-by-step explanation:
The correct form of the verb llenar that completes the conversation is option C. llene. In the given conversation, the speaker needs to see the doctor and asks for the paperwork or form to fill out. In this context, the second person singular form of the verb 'llenar' should be used, which is 'llene'.
Learn more about Spanish verb conjugation