ANS:D - all the above.

Specific yield depends on the distribution of pores, their shape, and grain size. The larger the surface area of the rocks or sediment particles per unit volume ("specific surface area"), the more water adheres to these surfaces. This decreases the specific yield in favour of specific retention. Specific yield is the ratio of volume of water drained by gravity by total volume of water in the aquifer. It depends on the permeability of the soil. Specific yield for most of the aquifer such as sand and gravel varies between 15% to 30%. The Specific Retention (Sr) of a rock or soil is the ratio of the volume of water a. Rock can retain against gravity to the total volume of the rock. Therefore, the total porosity is equal to the volume or water that a rock will yield.