—Michael likes flying around the world.

—I think being a             is just right for him. [ ]

A. pilot

B. policeman

C. cook

D. doctor

如图所示，杠杆OA 的B 点挂着一重物，A 端用绳子吊在滑环M 下，此时OA 恰好成水平，且A 点与圆弧架PQ 的圆心重合，那么当滑环M从P 点逐渐滑到Q 点的过程中，绳子对A 端拉力的大小将    

A．保持不变    

B．逐渐增大    

C．逐渐减少    

D．由大变小再变大