Aldosterone acts mainly at the renal tubules and stimulates the reabsorption of ____(I)____ and excretion of _____(II)_____ ions.
In the above, I and II are

	I	II
1.	Sodium and water	Potassium and phosphate
2.	Sodium and potassium	Phosphate and water
3.	Potassium and phosphate	Sodium and water
4.	Phosphate and water	Sodium and potassium

Aldosterone acts mainly at the renal tubules and stimulates the reabsorption of sodium and water and excretion of potassium and phosphate ions.

Adrenal cortex secretes aldosterone. This hormone stimulates the principal cells in the collecting ducts to reabsorb more Na⁺ and secrete more K⁺. Absorption of Na⁺ leads to reabsorption of water due to osmosis. It causes an increase in blood volume and blood pressure.