Explanation:

- Harsh drove for a total of 4 hours: 1 hour at 50 km/h and 3 hours at 60 km/h.

- In the first hour, he covered a distance of \(50 \, \text{km/h} \times 1 \, \text{hour} = 50 \, \text{km}\).

- In the next three hours, he covered a distance of \(60 \, \text{km/h} \times 3 \, \text{hours} = 180 \, \text{km}\).

- Total distance covered is \(50 \, \text{km} + 180 \, \text{km} = 230 \, \text{km}\).

- Average speed is the total distance divided by the total time: \(\frac{230 \, \text{km}}{4 \, \text{hours}}\).

- This equals 57.5 km/h.

Therefore, the correct average speed is:

- Option: 2 - 57.5 km/h