Question

José y Pedro van a __________esa canción. canta cantamos cantan cantar

Answer 1

Cantar would be the right one.

Answer 2

cantan

Step-by-step explanation:

Because it makes sense in english it would be

Jose and Pedro are going to sing this song.

and if you were to use cantamos it would be

Jose and Pedro are going we sing this song.

It doesn't make sense at all.