Right answer is (a) Keenest Demand
Best explanation: While fixing the capacity of a canal the main important that should be kept in mind is the keenest demand, but not the average demand. For instance, let rice require 160 cm of water during 320 days which gives an outlet factor of 1728 hectares/cumec. (i.e D = 864B/∆ = 864 x 320 / 160 = 1728).