According to the Central Pollution Control Board, particles that are responsible for causing great harm to human health are of diameter

Options

A. 2.50 micrometers
B. 5.00 micrometers
C. 10.00 micrometers
D. 7.5 micrometers.

Explanation

To solve the question regarding the diameter of particles that are responsible for causing great harm to human health, according to the Central Pollution Control Board, follow these steps:

### Step-by-Step Solution:

1. **Understand the Context**: The question is about particulate matter and its impact on human health. Particulate matter is a significant contributor to air pollution, and understanding its size is crucial for assessing health risks.

2. **Identify the Types of Particulate Matter**: Particulate matter can be categorized into two types:
- **Settleable Particles**: These are larger particles, typically greater than 10 micrometers in diameter, which tend to settle down due to gravity.
- **Suspended Particles**: These are smaller particles, usually less than 10 micrometers in diameter, which remain suspended in the air.

3. **Focus on Health Impact**: The Central Pollution Control Board has specified that particles of a certain size are particularly harmful to human health. The emphasis is on particles that are 2.5 micrometers or smaller.

4. **Select the Correct Option**: From the options provided:
- A) 2.50 micrometers
- B) 5 micrometers
- C) 10 micrometers
- D) 7.5 micrometers

The correct answer is **A) 2.50 micrometers**, as these particles are classified as the most harmful according to the Central Pollution Control Board.

5. **Conclusion**: Particles with a diameter of 2.5 micrometers or less are associated with serious health risks, including respiratory diseases.

### Final Answer:
**The diameter of particles that are responsible for causing great harm to human health, according to the Central Pollution Control Board, is 2.50 micrometers.**

---