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


[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].