Explanation:

- To find the average speed, we need total distance divided by total time taken.

- The first part: 120 km at 80 km/h ? time = 120/80 = 1.5 hours.

- The second part: 100 km at 40 km/h ? time = 100/40 = 2.5 hours.

- The return: Total distance so far is 220 km, so return is 220 km at 75 km/h ? time = 220/75 ˜ 2.93 hours.

- Total distance travelled = 120 + 100 + 220 = 440 km.

- Total time taken = 1.5 + 2.5 + 2.93 ˜ 6.93 hours.

- Average speed = 440 / 6.93 ˜ 63.46 km/h.

- Option 1 (63.46 km/h) is correct.

- Other options do not match this calculation.

Option 1: 63.46 km/h is the correct answer.