Final answer:
The correct verb form to complete the conversation is 'voy.'
Step-by-step explanation:
The correct verb form to complete the conversation is voy. The question is asking if Diego will teach Carolina to play the guitar, and Carolina responds with 'Sí, te voy a enseñarlo,' which means 'Yes, I am going to teach you.' The verb form 'voy' is the first person singular of the verb 'ir' (to go) in the present tense.
Learn more about Verb forms in Spanish