Assertion : the quasifluid nature of lipid enables lateral movement pof proteins within the overall bilayer.
Reason : This ability to move within the membrane is called fluidity and is important for cell growth.

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.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the quasi-fluid nature of lipids allows for the lateral movement of proteins within the lipid bilayer of the cell membrane. This is true because the lipids in the membrane are not rigid; they can move and shift, which enables proteins to move laterally.

2. **Understanding the Reason**:
- The reason given is that this ability to move within the membrane is called fluidity and is important for cell growth. Fluidity refers to the flexibility and movement of the components within the membrane, which is indeed crucial for various cellular processes, including growth.

3. **Evaluating the Relationship**:
- While both the assertion and reason are true statements, the reason does not specifically explain why the assertion is true. The assertion focuses on the movement of proteins due to the quasi-fluid nature of lipids, while the reason discusses fluidity in a broader context, including cell growth.

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

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

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