The correct answer is (b) 45 km/hr.
The average speed is not just the average of 60 km/hr and 40 km/hr. This is because the person travels for different distances at different speeds. To calculate the average speed, we need to consider the total distance traveled and the total time taken.
The total distance traveled is 2 * 60 = 120 km.
The total time taken is 60 / 60 + 60 / 40 = 3 hours.
Therefore, the average speed is 120 / 3 = 40 km/hr.
Option (a) is incorrect because it is the average of the two speeds, but it does not take into account the total distance traveled.
Option (c) is incorrect because it is the average speed of the first leg of the journey, but it does not take into account the second leg of the journey.
Option (d) is incorrect because it is the average speed of the second leg of the journey, but it does not take into account the first leg of the journey.