ANS:A - cm²/sec

The unit of volumetric diffusivity is cm^2/sec. Diffusivity is a measure of how quickly a substance diffuses through a medium. Volumetric diffusivity specifically refers to the diffusivity of a substance in a fluid per unit volume of the fluid. The unit of volumetric diffusivity is typically expressed in square centimeters per second (cm^2/sec). This unit indicates the area over which diffusion occurs (square centimeters) divided by the time it takes for diffusion to occur (seconds).