Dialysis fluid contains all the constituents as in plasma except:

The correct option is C Nitrogenous wastes
The process of filtering the blood using artificial kidney is known as dialysis. It is a method of removing excess water, nitrogenous wastes (urea) and toxins from the blood in the patient. It is also called renal replacement therapy. Dialysis fluid contains all constituents as in plasma except the nitrogenous waste (Urea).

So, the correct answer is 'Nitrogenous waste'.