For designing the venturi head,

• A. width of the throat should not be less than one-third of the bed width of main canal
• B. width of the throat should not be less than the width obtained from the formula B = Q / 1.2d^3/2, where d is the difference in levels of F.S.L. and sill
• C. minimum throat width should not be less than 60 cm
• D. all the above.