A hot-air balloon moves at constant velocity and stays at a constant height above the ground. The diagram shows the four forces acting on the balloon, and no others. Which statement is correct?
- AW and Y are equal, X and Z are equal.
- BW and Y are equal, X is greater than Z.
- CX and Z are equal, Y is greater than W.
- DY is greater than W, X is greater than Z.