Final answer:
The verb to fill in the blank is 'tienes'.
Step-by-step explanation:
The correct verb to fill in the blank is tienes. In Spanish, when asking someone's age, we use the verb tener which means 'to have'. The correct form of the verb for the second person singular informal 'tú' is 'tienes', which means 'you have'.
Learn more about Using the verb 'tener' to ask someone's age in Spanish