A person aiming to reach the exactly opposite point on the bank of a stream is swimming with a speed of `0.5(m)/(s)` at an angle of `120^@` with the direction of flow of water. The speed of water in the stream is
A. `1m//s`
B. `0.5m//s`
C. `0.25m//s`
D. `0.433m//s`