Rain water is falling vertically downward with velocity `v`. When velocity of wind is `u` in horizontal direction, water is collected at the rate of `R m^(3)//s`. When velocity of wind becomes `2u` in horizontal direction. The rate of collection of water in vessel is
A. `R`
B. `R/2`
C. `2R`
D. `(Rsqrt(4u^(2)+v^(2)))/(sqrt(u^(2)+v^(2)))`