**Core Concept**
The site of action of Antidiuretic Hormone (ADH), also known as Vasopressin, is a critical physiological process that regulates water reabsorption in the kidneys. ADH acts on specific receptors in the renal collecting ducts to promote water reabsorption, thereby concentrating the urine and maintaining proper fluid balance in the body.

**Why the Correct Answer is Right**
ADH binds to V2 receptors in the basolateral membrane of the principal cells in the renal collecting ducts. This binding activates a G-protein coupled signaling pathway, which increases the expression and insertion of aquaporin-2 water channels into the apical membrane. The increased aquaporin-2 channels facilitate water reabsorption from the lumen into the interstitium, leading to concentrated urine and reduced urine volume.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because ADH does not primarily act on the renal cortex, which is involved in sodium reabsorption and glomerular filtration.
* **Option B:** This option is incorrect because ADH does not directly stimulate the release of ADH from the posterior pituitary. The posterior pituitary releases ADH that is synthesized in the hypothalamus.
* **Option C:** This option is incorrect because ADH does not act on the adrenal glands to regulate aldosterone secretion. Aldosterone is a mineralocorticoid hormone that regulates sodium and potassium balance.

**Clinical Pearl / High-Yield Fact**
ADH deficiency or resistance can lead to diabetes insipidus, a condition characterized by excessive thirst and polyuria due to inadequate water reabsorption in the kidneys.

**Correct Answer:** C. Collecting ducts.