Rate at which plasma is cleared of solute free water is known as:: (A) Free water clearance, (B) Bound water clearance, (C) Water clearance rate, (D) Solute level clearance
Answer is A. Free Water Clearance: 

Is regulated by ADH. 
It is the rate at which plasma is cleared of solute free water.

​Free-water clearance (CH20) is calculated as the difference between water excretion (urine flow rate) and osmolar clearance: