Which tubule helps in maintaining the pH and ionic balance of the body fluids by selective secretion of ions into filtrate and by absorption of HCO₃^– from it?

Proximal Convoluted Tubule

The correct answer is Option (2) - Proximal Convoluted Tubule

Proximal Convoluted Tubule (PCT) is lined by simple cuboidal brush border epithelium which increases the surface area for reabsorption. Nearly all of the essential nutrients, and 70-80 per cent of electrolytes and water are reabsorbed by this segment. PCT also helps to maintain the pH and ionic balance of the body fluids by selective secretion of hydrogen ions, ammonia and potassium ions into the filtrate and by absorption of HCO₃ ^– from it.