Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The glomerular filtrate becomes increasingly hypertonic as it moves down the descending limb of the loop of Henle. Reason (R): The descending limb of the loop of Henle is permeable to water but almost impermeable to electrolytes. In the light of the above statements, choose the correct answer from

Step-by-step solution

Assertion (A) is true because as the filtrate flows down the descending limb of the loop of Henle, water moves out of the tubule into the hyperosmotic medullary interstitium, concentrating the filtrate and making it hypertonic. Reason (R) is true because the descending limb is permeable to water but almost impermeable to electrolytes. This selective permeability is exactly what causes the water efflux and the resulting concentration of the filtrate. Therefore, both (A) and (R) are true, and (R) is the correct expla