[单选题]
The driver of a motorboat that can move at 10 m5td kt9tleaf t-5q2s /cuq z,dw h.x8rxx 81*s0iwm5a/s in still water wishes to travel directly across a narrow strait in which the current flows at 5.0 m/s. At what a cx8is hzr8wx m*5xa.wqud01,ngle upstream should the driver head the boat?
A. $27^{\circ}$
B. $30^{\circ}$
C. $60^{\circ}$
D. $63^{\circ}$
