All of the following pairs of hormones are antagonistic, expect

Options

A. Calcitonin and parathormone
B. Cortisol and insulin
C. Insulin and glucagon
D. Calcitriol and Collip's hormone

Answer

To solve the question regarding which pair of hormones is not antagonistic, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Antagonistic Hormones**: Antagonistic hormones are pairs of hormones that have opposite effects on the same physiological function. For example, one hormone may increase a certain level in the body while the other decreases it.

2. **Analyze the Given Hormone Pairs**:
- **Calcitonin and Parathormone**: Calcitonin lowers blood calcium levels, while parathormone increases blood calcium levels. These hormones are antagonistic.
- **Cortisol and Insulin**: Insulin lowers blood glucose levels, whereas cortisol raises blood glucose levels. These hormones are also antagonistic.
- **Insulin and Glucagon**: Insulin decreases blood glucose levels, while glucagon increases blood glucose levels. These hormones are antagonistic as well.
- **Calcitriol and Parathormone**: Calcitriol (also known as active vitamin D) and parathormone both work to increase blood calcium levels. They do not have opposing effects; instead, they work together to achieve the same outcome.

3. **Identify the Non-Antagonistic Pair**: From the analysis, the pair that does not exhibit antagonistic behavior is **Calcitriol and Parathormone** because both hormones promote an increase in blood calcium levels.

4. **Conclusion**: Therefore, the correct answer to the question is the pair of hormones that are not antagonistic, which is **Calcitriol and Parathormone**.

### Final Answer:
The pair of hormones that are not antagonistic is **Calcitriol and Parathormone**.