<prompt> Which one of the following statements regarding water reabsorption in the tubules is true?The bulk of water reabsorption occurs secondary to Na reabsorptionMajority of facultative reabsorption occurs in proximal tubuleObligatory reabsorption is ADH dependent20 of water is always reabsorbed irrespective of water balance  <response>: Maximum of filtered water 60-70 is reabsorbed in the proximal tubule, with or without Vasopressin. This is independent of the fluid and electrolyte status of the body and is caused by the osmotic gradient created by Na reabsorption.Obligatory water reabsorption- Independent of ADH- 85- Proximal tubule- 60-70- Descending limb of loop of Henle- 15Facultative water reabsorption- ADH dependent- 15This depends on fluid and electrolyte status of the body- Late distal tubule- Cortical collecting ductMedullary collecting duct 