Correct choice is (a) Solution is being dialyzed
Best explanation: In dialysis, the solution being dialyzed is referred to as retentate. As compared to diffusate which is solvent outside. The ratio of Retentate volume and diffusate volume is the rate limiting factor for dialysis. Membrane is a thin film through which dialysis occurs. Small molecules are those which pass through the dialysis membrane. Large molecules cannot pass through the membrane.