Multi-select problem: How does the next paragraph end?

Some boys are inside a gym. They take turns stacking a pile of tires. after each addition

Options are: A). , they put a silver one on top of the red one. B). , one of them jumps and stands at the top. C). a new shot of the tires, they place them on each truck and put them on the front. D). , they point one pump and put it in their tires.
B).