Hormone responsible for aggressive behaviour of an animal is

Options

A. Adrenaline
B. Thyroxine
C. ADH
D. Testosterone.

Answer

To determine the hormone responsible for aggressive behavior in animals, we can analyze the provided options step by step.

### Step 1: Analyze the Options
We have four options to consider:
1. Adrenaline
2. Thyroxine
3. ADH (Antidiuretic Hormone)
4. Testosterone

### Step 2: Evaluate Each Hormone
- **Adrenaline**: This hormone is secreted by the adrenal medulla and is often referred to as the "emergency hormone." It is released in response to stress or emergencies and plays a significant role in the fight-or-flight response, which can lead to aggressive behavior in animals.

- **Thyroxine**: Secreted by the thyroid gland, thyroxine primarily regulates metabolism and increases oxygen consumption in metabolically active tissues. It is not directly linked to aggressive behavior.

- **ADH (Antidiuretic Hormone)**: Also known as vasopressin, ADH is secreted from the posterior pituitary gland and primarily functions to increase water reabsorption in the kidneys, thus regulating water balance in the body. It does not influence aggressive behavior.

- **Testosterone**: This is a male sex hormone produced in the testes. While it is involved in the development of secondary sexual characteristics and can influence behavior, it is not primarily responsible for aggressive behavior in the same way adrenaline is.

### Step 3: Conclusion
Based on the analysis, **Adrenaline** is the hormone that is most closely associated with aggressive behavior in animals due to its role in the fight-or-flight response during stressful situations.

### Final Answer
The hormone responsible for aggressive behavior of an animal is **Adrenaline**.

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