The hormone responsible for maintaining the diurnal rhythm and sexual behaviour in animals is

Options

A. FSH
B. aldosterone
C. androgens
D. melatonin

Answer

To solve the question regarding the hormone responsible for maintaining the diurnal rhythm and sexual behavior in animals, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**:
- We need to identify which hormone is linked to maintaining the diurnal rhythm and sexual behavior in animals.

2. **Analyzing the Options**:
- The options provided are:
- A. FSH (Follicle Stimulating Hormone)
- B. Aldosterone
- C. Androgens
- D. Melatonin

3. **Evaluating Each Option**:
- **FSH (Follicle Stimulating Hormone)**:
- This hormone is produced by the pituitary gland and is primarily involved in the growth of ovarian follicles in females and spermatogenesis in males. It does not play a significant role in maintaining diurnal rhythms.
- **Aldosterone**:
- Aldosterone is a hormone produced by the adrenal glands that regulates sodium and potassium levels in the body. It is not involved in diurnal rhythms or sexual behavior.
- **Androgens**:
- Androgens, such as testosterone, are hormones that influence male sexual characteristics and reproductive functions. While they are involved in sexual behavior, they do not regulate diurnal rhythms.
- **Melatonin**:
- Melatonin is produced by the pineal gland and is crucial for regulating the sleep-wake cycle (diurnal rhythm). It also influences various physiological processes, including sexual behavior.

4. **Conclusion**:
- Based on the analysis, the hormone that maintains the diurnal rhythm and influences sexual behavior in animals is **Melatonin**.

### Final Answer:
The hormone responsible for maintaining the diurnal rhythm and sexual behavior in animals is **Melatonin**.

---