Assertion : Rudolf Virchow modified the hypothesis of cell theory given by Schleiden and Schwann.
Reason : Cell theory says that all cells arise from pre-existing cells.

Options

A. If both assertion and reason are true amnd 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.

Answer

To solve the assertion-reason question regarding Rudolf Virchow and the cell theory, we can break it down step by step:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Rudolf Virchow modified the hypothesis of cell theory given by Schleiden and Schwann."
- This means we need to recognize that Virchow contributed to the cell theory by adding to the ideas proposed by Schleiden and Schwann.

2. **Understanding the Reason**:
- The reason states that "Cell theory says that all cells arise from pre-existing cells."
- This is a fundamental principle of the cell theory, which was indeed articulated by Virchow.

3. **Historical Context**:
- Schleiden and Schwann formulated the original cell theory, which included the idea that all living organisms are made of cells.
- However, their theory did not explain how new cells are formed.

4. **Virchow's Contribution**:
- Rudolf Virchow modified the existing cell theory by stating that "all cells arise from pre-existing cells," which clarified the process of cell division and the origin of new cells.

5. **Evaluating the Assertion and Reason**:
- Both the assertion and the reason are correct:
- The assertion correctly identifies Virchow's modification of the cell theory.
- The reason accurately states a key component of the cell theory as modified by Virchow.

6. **Correct Relationship**:
- While both statements are true, the reason does not directly explain the assertion. The assertion is about Virchow's modification, while the reason is a statement about the cell theory itself.

7. **Conclusion**:
- Therefore, the correct answer is that both the assertion and reason are correct, but the reason is not the correct explanation of the assertion.

### Final Answer:
Both the assertion and reason are correct, but the reason is not the correct explanation of the assertion.

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