Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Mammals have the ability to produce a concentrated urine. Reason (R): The counter current mechanism maintains an increasing osmolarity towards the inner medullary interstitium, which facilitates water reabsorption from the collecting duct. In the light of the above statements, choose the most appro

Step-by-step solution

Assertion (A) is true because mammals, including humans, can produce urine that is significantly more concentrated than the initial filtrate. Reason (R) is true and correctly explains Assertion (A). The counter current mechanism operating between the two limbs of the Henle's loop and the vasa recta maintains an increasing osmolarity towards the inner medullary interstitium. This gradient is essential because it allows the passive reabsorption of water from the collecting duct, thereby concentrating the filtrate and