The preferred method of controlling external bleeding is by（）.

A.angle that the propeller makes with a free stream of water
B.angle that the propeller makes with the surface of the water
C.number of feet per revolution the propeller is designed to advance in still water without slip
D.positive pressure resulting from the difference of the forces on both sides of the moving propeller in still water without slip

A.a margin of safety is provided should the line part
B.the towline will wear more evenly
C.there will be less stress on the towline
D.a slight increase in speed will be realized

A.advance
B.head reach
C.pitch
D.transfer