A trapezoidal section of an open channel has side slope 2H:1V. If bottom width is 'b’ and depth ‘d’, the relation between b & d for most economical trapezoidal section of the channel is:

A

b = 0.472 d

B

b/d = 0.5

C

$$b^2 = 0.3 d^2$$

D

$$d = \sqrt b$$