The apparent depth of water in cylindrical water tank of diameter 2 R cm is reducing at the rate of x `cm //min` when water is being drained out at a constant rate .The amount of water drained in c.c. per minute is `(mu_(1) `= refractive index of air, `mu_(2)` = refractive index of water)

Options

A. `(xpiR^2 mu_1)/(mu_2)`
B. `(xpiR^2mu_2)/(mu_1)`
C. `(2 pi R mu_1)/(mu_2)`
D. `(2piRmu_2)/(mu_1)`.