Physiology The primary site of action of antidiuretic hormone is on the: A Distal tubules and collecting ducts in the kidney B Afferent arterioles of the glomeruli C Thirst center in the hypothalamus D Osmoreceptors in the hypothalamus 💡 Explanation The primary site of action of antidiuretic hormone is on the: ✓ Correct Answer: A. Distal tubules and collecting ducts in the kidney