In frogs, the metamorphosis of a tadpole into an adult frog is under the control of a hormone. Which hormone stimulates metamorphosis in frogs?

Options

A. Testosterone
B. Adrenalin
C. Estrogen
D. Thyroxin

Answer

To answer the question about which hormone stimulates the metamorphosis of a tadpole into an adult frog, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Process**: Understand that the question is about the metamorphosis of a tadpole into an adult frog. This process is crucial in the life cycle of frogs.

2. **Consider the Hormones**: The question provides four options:
- Testosterone
- Adrenaline
- Estrogen
- Thyroxin

3. **Analyze Each Hormone**:
- **Testosterone**: This hormone is primarily involved in the development of male reproductive tissues and characteristics. It does not play a role in the metamorphosis of frogs.
- **Adrenaline**: This hormone is secreted by the adrenal glands and is responsible for the 'fight or flight' response, increasing heart rate and energy. It does not control metamorphosis.
- **Estrogen**: This hormone is produced in the ovaries and regulates the menstrual cycle in females. It is not involved in frog metamorphosis.
- **Thyroxin**: This hormone is secreted by the thyroid gland and is essential for regulating metabolism and growth. Importantly, it plays a crucial role in the metamorphosis of tadpoles into adult frogs.

4. **Conclude the Correct Answer**: Based on the analysis, the hormone that stimulates metamorphosis in frogs is **Thyroxin**.

### Final Answer:
The hormone that stimulates metamorphosis in frogs is **Thyroxin**.

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