Final answer:
The correct verb form to fill in the blank is 'vamos'.
Step-by-step explanation:
The correct verb form to fill in the blank in the sentence is A. vamos. The subject 'tú y yo' is plural, so the corresponding verb form in Spanish is 'vamos,' which means 'we go' or 'we are going.' The other verb forms 'vais,' 'voy,' and 'vas' do not match the subject correctly.
Learn more about Spanish verb conjugation