The principal action in changing from transit to survival draft in the event heavy weather threatens is（）.

A.direct pressure on the wound
B.elevating the wounded area
C.pressure on a pressure point
D.a tourniquet above the wound

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