Given below are two statements: Statement I: NaCl is returned to the medullary interstitium by the ascending portion of the vasa recta. Statement II: Small amounts of urea enter the descending limb of the loop of Henle and are transported back to the interstitium by the distal convoluted tubule. In the light of the above statements, choose the most appropriate answer from the options given below.

Step-by-step solution

According to the countercurrent mechanism in the human kidney, NaCl is transported by the ascending limb of Henle's loop and is exchanged with the descending limb of the vasa recta. This NaCl is then returned to the medullary interstitium by the ascending portion of the vasa recta. Thus, Statement I is correct. Small amounts of urea enter the thin segment of the ascending limb of Henle's loop (not the descending limb) and are transported back to the medullary interstitium by the collecting tubule (not the distal co