The ion channel are .......to different ions:

Options

A. Completely permeable
B. Impermeable
C. Selectively permeable
D. Both A and C

Answer

To answer the question "The ion channels are .......to different ions," we need to evaluate the options provided and determine the correct description of ion channels.

### Step-by-Step Solution:

1. **Understanding Ion Channels**: Ion channels are specialized proteins that allow ions to pass through the cell membrane. They play a crucial role in various physiological processes, including nerve impulse transmission and muscle contraction.

2. **Evaluating the Options**:
- **Option A: Permeable** - This suggests that the ion channels allow all ions to pass through without restriction. This is incorrect because not all ions can pass through every ion channel.
- **Option B: Impermeable** - This means that the ion channels do not allow any ions to pass through. This is also incorrect, as ion channels are designed to facilitate the movement of specific ions.
- **Option C: Selectively Permeable** - This indicates that ion channels allow only certain ions to pass through while restricting others. This is the correct description of ion channels.
- **Option D: Both A and C** - Since option A is incorrect, this option is also incorrect.

3. **Conclusion**: Based on the evaluation of the options, the correct answer is that ion channels are **selectively permeable** to different ions.

### Final Answer:
The ion channels are **selectively permeable** to different ions.

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