Concentration of urine is controlled by

Options

A. Vasopressin
B. Aldosterone
C. Insulin
D. Adrenaline

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the regulation of urine concentration in the body. This involves understanding which hormones are involved in the process.

2. **Identifying the Options**: The options provided are:
- A) Vasopressin
- B) Aldosterone
- C) Insulin
- D) Adrenaline

3. **Analyzing Each Option**:
- **Vasopressin (Antidiuretic Hormone)**: This hormone is secreted by the posterior pituitary gland. Its primary function is to regulate the reabsorption of water in the kidneys, specifically in the collecting ducts. When vasopressin is released, it increases water reabsorption, leading to more concentrated urine.

- **Aldosterone**: This hormone is secreted by the adrenal cortex and is primarily involved in regulating sodium and potassium levels, as well as water balance. While it does influence blood pressure and fluid balance, its primary role is not directly related to urine concentration.

- **Insulin**: This hormone is produced by the pancreas and is responsible for regulating glucose levels in the blood. It does not play a direct role in urine concentration.

- **Adrenaline**: Secreted by the adrenal medulla during stress or emergency situations, adrenaline affects heart rate and blood flow but does not directly control urine concentration.

4. **Conclusion**: Based on the analysis, the hormone that primarily controls the concentration of urine is **Vasopressin** (option A). It enhances water reabsorption in the kidneys, leading to concentrated urine.

### Final Answer:
The concentration of urine is controlled by **Vasopressin** (Option A).

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