Identify the odd one among the following and justify that.
Polythene, Egg membrane, Cell membrane, Onion peel

Explanation

To identify the odd one among the following options: Polythene, Egg membrane, Cell membrane, and Onion peel, we can follow these steps:

### Step 1: Understand the Properties of Each Option
- **Polythene**: A synthetic plastic material used for packaging. It is impermeable, meaning it does not allow substances to pass through.
- **Egg Membrane**: A natural membrane that surrounds the egg. It is semi-permeable, allowing certain molecules to pass through while blocking others.
- **Cell Membrane**: A biological membrane that separates and protects the interior of a cell from the external environment. It is also semi-permeable.
- **Onion Peel**: The outer layer of an onion, which acts as a protective barrier. It is semi-permeable as well.

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