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^(circ)` east of north
C. `30^(circ)` north of west
D. `60^(circ)` east of north

Answer

A

Explanation

For shortest time to cross, velocity should be maximum towards north as river velocity does not take any part to cross.