Which of the following is the best concise definition of a diuretic in the clinical context?

An enzyme inhibitor that permanently stops kidney function and is used clinically only in end-stage renal disease to reduce urine output to zero.

An agent that increases urine production, thereby promoting water and some electrolyte excretion.

A substance that exclusively increases fecal fat excretion and has no effect on urinary volume, hydration status, or electrolyte balance.

A dietary supplement that increases cellular water retention and prevents urinary losses through enhanced tubular reabsorption and long-term intravascular expansion.