The correct answer is salimos. This means We left school at three in the afternoon. Te other 3 would say: come out, you go out, or go out.
Mi profesora se pone agitada
Mis amigos se divierten
Yo me enojo
Mis amigos y yo nos volvemos locos
Los alumnos se aburren en la clase
The answer is definitely a
i believe it should be "add the new ending to the infinitive" and "don't drop the -ar, -er, and -ir"