Assertion :- Facilitated diffusion follows saturation kinetics.
Reason:- Facilitated diffusion is carried out by special protein carriers

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 the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Facilitated diffusion follows saturation kinetics." This means that the rate of facilitated diffusion increases with the concentration of the substance being transported until it reaches a maximum rate, beyond which it cannot increase further, even if the concentration continues to rise.

2. **Understanding the Reason**: The reason provided is that "Facilitated diffusion is carried out by special protein carriers." This indicates that specific proteins in the cell membrane facilitate the transport of molecules across the membrane.

3. **Connection Between Assertion and Reason**: The reason explains the assertion because the saturation kinetics in facilitated diffusion is due to the limited number of protein carriers available. Once all available carriers are occupied, the rate of transport cannot increase, leading to saturation.

4. **Passive Transport Mechanism**: Facilitated diffusion is a type of passive transport, meaning it does not require energy (ATP) and occurs along the concentration gradient (from high to low concentration).

5. **Conclusion**: Since both the assertion and reason are true, and the reason correctly explains the assertion, we conclude that the correct answer 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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