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 / 1.2d3/2, 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. length of the throat should be 2.5 times the depth measured to F.S.L. in the main canal E. all the above