Explanation:

- Punit travels to his relative's place at 45 km/h.

- While returning, he drives at 40 km/h and takes 1 hour longer.

- Let the distance be $D$ km.

To his relative's place:

- Time taken = $\frac{D}{45}$.

Returning home:

- Time taken = $\frac{D}{40}$.

- It takes an hour longer to return, so:

$$

\frac{D}{40} = \frac{D}{45} + 1

$$

- Solving this equation:

$$

\frac{D}{40} - \frac{D}{45} = 1

$$

$$

\frac{5D}{1800} = 1

$$

$$

D = 360 \text{ km}

$$

- Option 4: 360 km is correct.

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