Assertion : Fossil fuels are important source of energy.
Reason : Fossil fuels provide energy to different industries.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

### Step-by-Step Text Solution:

1. **Understanding the Assertion**: The assertion states that "Fossil fuels are an important source of energy." This means that fossil fuels, which include coal, petroleum, and natural gas, play a significant role in providing energy for various applications.

2. **Understanding the Reason**: The reason given is that "Fossil fuels provide energy to different industries." This indicates that fossil fuels are utilized in various sectors, such as manufacturing, transportation, and agriculture, to generate the energy required for their operations.

3. **Evaluating the Assertion and Reason**: Both the assertion and the reason are true statements. Fossil fuels are indeed a major source of energy, and they are widely used in different industries to power machinery, vehicles, and other equipment.

4. **Justification of the Reason**: The reason provided explains why the assertion is true. Since fossil fuels are essential for the functioning of many industries, their importance as a source of energy is justified.

5. **Conclusion**: Based on the analysis, both the assertion and reason are correct, and the reason effectively explains the assertion. Therefore, the correct option is that both the assertion and reason are true, and the reason is the correct explanation for the assertion.