Final answer:
The correct verb form to complete the sentence is 'vendrá' (option OA).
Step-by-step explanation:
In the given sentence, the subject is 'Juan', which is a singular noun. Therefore, we need to use the verb form that agrees with a singular subject. The correct verb form to complete the sentence is 'vendrá' (option OA). 'Vendrá' is the third-person singular form of the verb 'venir' (to come) in the future tense.
Learn more about Verb forms in Spanish