Q.Enumerate the role of kidney as an endocrine gland.

The kidney secretes Renin (regulates blood pressure via the renin-angiotensin-aldosterone system) and Calcitriol (the active form of vitamin D, which regulates calcium absorption) — so the correct pair is (i) and (iii).

Let's evaluate each hormone listed:

1. Renin — secreted by the juxtaglomerular cells of the kidney; it initiates the renin-angiotensin-aldosterone pathway that raises blood pressure when renal blood flow/pressure falls. TRUE, kidney hormone.
2. Gastrin — secreted by G-cells of the stomach (pyloric region), stimulates gastric acid secretion. NOT a kidney hormone.
3. Calcitriol — the active, hormonal form of vitamin D, produced by the kidney (via hydroxylation of a vitamin D precursor); it promotes intestinal calcium absorption. TRUE, kidney hormone. …