What happens next?

People dance in a studio while a trainer shows a sign. then

Choices:
A). , people continue dance on the floor and then the trainer show.;
B). , people dance in an exercise room, then the trainer is in the auditorium.;
C). , a group of little girls dance together while a trainer explains the moves.;
D). , the trainer see the students, but he with a rucksack.;
C).