Given below are the steps involved in the generation and conduction of nerve impulse. Arrange them in proper sequence and select the correct option.
I. Rapid influx of `Na^+` ions followed by reversal of polarity at the site of application of stimulus.
II. Reversal of polarity and generation of action potential at a point ahead of the point of application of stimulus.
III. Development of free permeability to `Na^+` ions at the site of application of stimulus.
IV. Arrival of the impulse generated at the first site to the second site.
V. Rise in permeability of `K^+` ions and restoration of the resting potential of the membrane.

Options

A. V , II, III, IV , I
B. I, III , II , V , IV
C. III, II , I, IV , V
D. III , I, II , IV , V

Answer

To solve the question regarding the sequence of events in the generation and conduction of a nerve impulse, we need to arrange the given steps in the correct order. Here’s how we can approach it step by step:

### Step-by-Step Solution:

1. **Step III: Development of free permeability to `Na^+` ions at the site of application of stimulus.**
- This is the initial step where the nerve membrane becomes permeable to sodium ions due to the application of a stimulus.

2. **Step I: Rapid influx of `Na^+` ions followed by reversal of polarity at the site of application of stimulus.**
- After the permeability increases, sodium ions rapidly enter the neuron, causing a change in polarity (depolarization) at the stimulated site.

3. **Step II: Reversal of polarity and generation of action potential at a point ahead of the point of application of stimulus.**
- As the depolarization occurs, it triggers the generation of an action potential at the adjacent area of the membrane, moving the impulse forward.

4. **Step IV: Arrival of the impulse generated at the first site to the second site.**
- The action potential travels along the neuron, reaching the next segment of the membrane.

5. **Step V: Rise in permeability of `K^+` ions and restoration of the resting potential of the membrane.**
- Finally, after the action potential has passed, potassium channels open, allowing `K^+` ions to exit the cell, restoring the resting membrane potential.

### Correct Sequence:
The correct sequence of steps is:
**III → I → II → IV → V**

### Answer:
The correct option that matches this sequence is **Option 4: III, I, II, IV, V.**