Answer: Jugar
Explanation: We must complete the sentence:
"¿Vas a _____ al béisbol conmigo?"
Here the actuall verb is "vas", where the verbal person is "tu" or "vos"
Vos vas a...
tu vas a...
So the correct option that completes the blank is the verb non conjugated, "jugar"
¿Vas a jugar al béisbol conmigo?