Which one of the following is called intraspecific chemical messenger

Options

A. Pheromones
B. Prostaglandins
C. Corticotrophin
D. Catecholamines.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the term that refers to intraspecific chemical messengers. Intraspecific means communication within the same species.

2. **Analyzing the Options**:
- **Pheromones**: These are chemical substances secreted by an individual and detected by another individual of the same species, used for communication.
- **Prostaglandins**: These are lipid compounds derived from fatty acids that have various functions in the body, but they are not specifically for communication between individuals of the same species.
- **Corticotropin**: This is a hormone produced by the pituitary gland that stimulates the adrenal cortex, not related to intraspecific communication.
- **Catecholamines**: These are hormones produced by the adrenal medulla (like adrenaline and noradrenaline) and are involved in the body's response to stress, not specifically for communication between individuals of the same species.

3. **Identifying the Correct Answer**: Since pheromones are specifically used for communication between members of the same species, they are classified as intraspecific chemical messengers.

4. **Conclusion**: The correct option is **pheromones**.