The discharge through a wholly drowned orifice is given by (where H1 = Height of water (on the upstream side) above the top of the orifice, H2 = Height of water (on the downstream side) above the bottom of the orifice, and H = Difference between two water levels on either side of the orifice)

A. Q = Cd × bH₁ × √(2gh)

B. Q = Cd × bH2 × √(2gh)

C. Q = Cd × b (H2 - H1) × √(2gh)

D. Q = Cd × bH × √(2gh)

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