Depolarisation of nerve cell involves

Options

A. Influx of `K^(+)`
B. Influx of `Na^(+)`
C. Influx of `Ca^(2+)andCl^(-)`
D. Effux of `Na^(2+)`

Explanation

### Step-by-Step Solution:

1. **Understanding Resting State**:
- A nerve cell at rest has a negative charge inside and a positive charge outside. This condition is known as polarization.

2. **Stimulus Application**:
- When a stimulus is applied to a specific point on the nerve cell (let's call it point A), it triggers a change in the membrane's permeability.

3. **Membrane Permeability Change**:
- The application of the stimulus makes the membrane more permeable to sodium ions (Na+).

4. **Influx of Sodium Ions**:
- Sodium ions rapidly enter the cell due to the change in permeability. This influx of positively charged sodium ions causes the inside of the cell to become more positive.

5. **Reversal of Charge**:
- As sodium ions enter, the charge inside the membrane reverses from negative to positive. This change in charge is referred to as depolarization.

6. **Action Potential Generation**:
- The rapid influx of sodium ions and the resulting change in charge at point A generates an action potential, which is the electrical signal that propagates along the nerve cell.

7. **Conclusion**:
- Therefore, the depolarization of a nerve cell primarily involves the influx of sodium ions.

### Final Answer:
The depolarization of a nerve cell involves the influx of sodium ions.

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