ADH acts on
(a) Collecting tubule of kidney
(b) Loop of Henle
(c) Collecting ducts of testis
(d) None of the above

Options

A. Collecting tubule of kidney
B. Loop of Henle
C. Collecting ducts of tests
D. None of the above

Answer

To solve the question regarding the action of ADH (Antidiuretic Hormone), we can follow these steps:

### Step-by-Step Solution:

1. **Understand what ADH is**:
- ADH stands for Antidiuretic Hormone, which is also known as vasopressin. It is a hormone produced by the hypothalamus and released by the posterior pituitary gland.

2. **Identify the primary function of ADH**:
- The main function of ADH is to regulate water balance in the body by promoting water reabsorption in the kidneys. This helps to concentrate urine and reduce water loss.

3. **Determine where ADH acts in the kidney**:
- ADH specifically acts on the collecting ducts and collecting tubules of the nephron in the kidney. It increases the permeability of these structures to water, allowing more water to be reabsorbed back into the bloodstream.

4. **Evaluate the options provided**:
- (a) Collecting tubule of kidney - This is where ADH acts.
- (b) Loop of Henle - ADH does not primarily act here.
- (c) Collecting ducts of testis - This is not relevant to ADH.
- (d) None of the above - This is incorrect since option (a) is correct.

5. **Select the correct answer**:
- Based on the above analysis, the correct answer is (a) Collecting tubule of kidney.

### Final Answer:
ADH acts on (a) Collecting tubule of kidney.