Which of the following matches is not true for the hormone and their functions ?

Options

A. Thyroxine , maintenance of water and electrolyte balance
B. Cortisol : stimulate the formation of erythrocytes
C. Melatonin : influences pigmentation and menstural cycle
D. All of the above are corrctly matched.

Answer

To solve the question regarding which hormone-function match is not true, we need to analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Hormones and Their Functions**:
We need to look at the hormones mentioned: thyroxine, cortisol, and melatonin, and their respective functions.

2. **Evaluate Thyroxine**:
- **Function**: Maintenance of water and electrolyte balance.
- **Analysis**: Thyroxine, produced by the thyroid gland, primarily regulates metabolism, growth, and development. It is not primarily responsible for maintaining water and electrolyte balance. This function is more associated with hormones like aldosterone.

3. **Evaluate Cortisol**:
- **Function**: Stimulate the formation of erythrocytes (red blood cells).
- **Analysis**: Cortisol, a glucocorticoid hormone, is indeed involved in the stress response and can stimulate erythropoiesis indirectly during stress. This match is correct.

4. **Evaluate Melatonin**:
- **Function**: Influences pigmentation and menstrual cycle.
- **Analysis**: Melatonin is produced by the pineal gland and is involved in regulating sleep-wake cycles, and it does have some influence on pigmentation and menstrual cycles. This match is also correct.

5. **Conclusion**:
- The only incorrect match is for thyroxine, as it does not primarily maintain water and electrolyte balance. Therefore, the answer to the question is that the match for thyroxine is not true.

### Final Answer:
The match that is not true for the hormone and their functions is:
- **Thyroxine - Maintenance of water and electrolyte balance**.