Specific capacity or yield of wells, is generally expressed, as

Answer: Option D

Specific capacity, also known as the yield of wells, is a measure of the efficiency and productivity of a well. It is typically expressed as the volume of water a well can produce per unit time per unit drawdown per unit area. The appropriate units for expressing specific capacity are m3/hour/m2/m, which represents cubic meters of water per hour per square meter of well area per meter of drawdown.

This unit of measurement helps in comparing the performance of different wells and in assessing their sustainability for water supply purposes.