Which of the following pair of hormones are antagonistic in action ?

Options

A. Calcitonin and parathormone
B. Somatostatin and GHRH
C. Adrenaline and insulin
D. All of the above

Answer

To determine which pair of hormones are antagonistic in action, we need to analyze the functions of each hormone pair provided in the question.

### Step-by-Step Solution:

1. **Identify the Hormones:**
- The pairs of hormones given are:
1. Calcitonin and Parathormone
2. Somatostatin and Growth Hormone Releasing Hormone (GHRH)
3. Adrenaline and Insulin
4. All of the above

2. **Analyze the First Pair: Calcitonin and Parathormone:**
- **Calcitonin** is produced by the thyroid gland and functions to lower blood calcium levels.
- **Parathormone** (or parathyroid hormone) is produced by the parathyroid glands and functions to increase blood calcium levels.
- **Conclusion:** These two hormones have opposite effects on calcium levels in the blood, making them antagonistic.

3. **Analyze the Second Pair: Somatostatin and GHRH:**
- **Somatostatin** inhibits the release of growth hormone from the pituitary gland.
- **Growth Hormone Releasing Hormone (GHRH)** stimulates the release of growth hormone from the pituitary gland.
- **Conclusion:** These hormones also have opposite actions regarding growth hormone release, making them antagonistic.

4. **Analyze the Third Pair: Adrenaline and Insulin:**
- **Adrenaline** (or epinephrine) is produced by the adrenal medulla and is responsible for increasing blood glucose levels by stimulating glycogen breakdown.
- **Insulin** is produced by the pancreas and functions to lower blood glucose levels by promoting glucose uptake by cells.
- **Conclusion:** These hormones also work in opposition to each other regarding blood glucose levels, making them antagonistic.

5. **Final Conclusion:**
- Since all three pairs of hormones exhibit antagonistic actions, the correct answer is **All of the above**.

### Final Answer:
The pair of hormones that are antagonistic in action is **All of the above**.