Assertion : Classification is necessary to study all living organisms.
Reason : In classification, individuals are grouped into categories.

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 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 Solution:

1. **Understanding the Assertion**: The assertion states that "Classification is necessary to study all living organisms." This implies that without classification, it would be difficult to effectively study and understand the vast diversity of life.

2. **Understanding the Reason**: The reason provided is that "In classification, individuals are grouped into categories." This means that classification helps in organizing organisms based on shared characteristics, making it easier to study them.

3. **Evaluating the Assertion**: The assertion is true because classification allows scientists to manage the complexity of biological diversity. By grouping organisms, researchers can focus on specific categories, making it feasible to study them systematically.

4. **Evaluating the Reason**: The reason is also true because grouping individuals into categories is indeed a fundamental aspect of classification. This process aids in identifying relationships and differences among organisms.

5. **Determining the Relationship**: Since both the assertion and the reason are true, we need to determine if the reason correctly explains the assertion. The reason does explain why classification is necessary; it provides a method to organize and study organisms effectively.

6. **Conclusion**: Therefore, the correct option is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

### Final Answer:
Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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