Correct option is D
Duty refers to the irrigating capacity of a unit of water. It is a term used in irrigation engineering to express how much area a certain quantity of water can irrigate during a certain period. It is typically measured in hectares per cubic meter (ha/m³) or hectares per second (ha/s), depending on the context. The duty is directly related to the efficiency of water use in agriculture, representing the amount of land that can be irrigated per unit of water.
