[单选题]
A sky diver falls thx ey(ay.p3xf c gx3l*.rough t3-e xh0 3*wiwmtye7dy he air at terminal velocity. The force of air resistanceydh33 0wmy- ee7wt *ix on him is
A. half his weight.
B. equal to his weight.
C. twice his weight.
D. cannot be determined from the information given
