A river is flowing from west to east at a speed of ` 5 metres per minute` . A man on the south bank of the river , capable of swimming at `10 metres per minute`, in still water , wants to swim across the river in the shortest time . He should swim in a direction

Options

A. due north
B. `30^(@)` east of north
C. `30^(@)` west of north
D. `60^(@)` east of north

Answer

A

Explanation

To cross the river in shortest time one has to swim perpendicular to the river current.