Crop water use efficiency or consumptive water use efficiency (Ecu​) can be formulated as:

Correct option is C

Crop water use efficiency (Ecu) measures the amount of yield produced per unit of water consumed by the crop. It is expressed as:

where:
· YYY = Yield of the crop.
· GGG = Groundwater contribution.
· TTT = Transpiration losses.
· Es = Soil evaporation losses.
This equation evaluates how efficiently water is utilized for crop production.