Which of the following statements are correct?
I. Non-renewable resources are those which once used up cannot be replaced within a reasonable period of time.
II. Coal and natural gas are inexhaustible natural resources.
III. CNG is more polluting than petrol.
IV. The high temperature and high pressure inside the earth slowly converted the buried vegetation into coal

Options

A. I and II only
B. II and IV only
C. I, III and IV only
D. I and IV only

Explanation

To determine which statements are correct regarding non-renewable resources, coal, natural gas, and CNG, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement I: Non-renewable resources are those which once used up cannot be replaced within a reasonable period of time.**
- This statement is **correct**. Non-renewable resources, such as fossil fuels (coal, oil, natural gas), cannot be replenished in a human timeframe once they are depleted.

2. **Statement II: Coal and natural gas are inexhaustible natural resources.**
- This statement is **incorrect**. Coal and natural gas are finite resources; they exist in limited quantities and can be exhausted. Therefore, they are classified as exhaustible resources, not inexhaustible.

3. **Statement III: CNG is more polluting than petrol.**
- This statement is **incorrect**. Compressed Natural Gas (CNG) is generally considered to be a cleaner fuel compared to petrol. It produces fewer pollutants and greenhouse gases when burned, making it less polluting.

4. **Statement IV: The high temperature and high pressure inside the earth slowly converted the buried vegetation into coal.**
- This statement is **correct**. The formation of coal involves the transformation of plant material under conditions of high temperature and pressure over millions of years.

### Conclusion:
Based on the analysis:
- **Correct Statements**: I and IV
- **Incorrect Statements**: II and III

Thus, the correct answer is that statements I and IV are correct.