A river is flowing from west to east at a speed of 5 m min^-1. Aman on the south bank of the river, capable of swimming at 10 m min^-1 in still water, wants to swim across the river in the shortest time. Finally, he will move in a direction 

• A

  ${\tan }^{-1}\left(2\right)\mathrm{E}\text{ of }\mathrm{N}$

• B

  ${\tan }^{-1}\left(2\right)\mathrm{N}\text{ of }\mathrm{E}$

• C

  ${30}^{\circ }\mathrm{E}\text{ of }\mathrm{N}$

• D

  ${60}^{\circ }\mathrm{E}\text{ of }\mathrm{N}$