The critical depth in a channel can be produced
(A) By raising the bottom of the channel
(B) By lowering the bottom of the channel
(C) By decreasing the width of the channel
(D) Both (a) and (c) of above
(A) By raising the bottom of the channel
(B) By lowering the bottom of the channel
(C) By decreasing the width of the channel
(D) Both (a) and (c) of above