$ In osmosis, semipermeable membrane is a must.
! Cell wall is semipermeable.

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

To solve the question regarding osmosis and the properties of the cell wall, we can break it down into a step-by-step analysis:

### Step 1: Understand the Assertion
The assertion states that "in osmosis, a semipermeable membrane is a must."
- **Explanation**: Osmosis is a specific type of diffusion where water moves across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. The semipermeable membrane allows only certain substances (like water) to pass through while restricting others.

### Step 2: Evaluate the Reason
The reason states that "the cell wall is semipermeable."
- **Explanation**: The cell wall is a rigid structure that surrounds the cell membrane in plant cells. It is not semipermeable; rather, it is generally considered to be fully permeable, allowing all substances, including water, ions, and small molecules, to pass through without restriction.

### Step 3: Conclusion
Based on the evaluations:
- The assertion is **correct** because osmosis requires a semipermeable membrane for the process to occur.
- The reason is **incorrect** because the cell wall is not semipermeable; it is permeable to all substances.

### Final Answer
The correct answer to the question is that the assertion is correct, but the reason is incorrect.

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