If D1 and D2 are depths of water up-stream and down-stream of a hydraulic jump in rectangular channel, the loss of head at the jump is

A

$$\frac {(D_2 - D_1)^3}{D_1 D_2}$$

B

$$\frac {(D_2 - D_1)^3}{2 D_1 D_2}$$

C

$$\frac {(D_2 - D_1)^3}{3 D_1 D_2}$$

D

$$\frac {(D_2 - D_1)^3}{4 D_1 D_2}$$