Final answer:
The distance between the two cities is found by multiplying the velocity of 1.2 m/s by the travel time of 12,600 seconds, which equals 15,120 meters.
Step-by-step explanation:
To calculate the distance between two cities, you can use the formula distance = velocity × time. Given that the velocity of the train is 1.2 meters per second (m/s) and the time taken is 12,600 seconds, you would multiply the two together to find the distance.
distance = 1.2 m/s × 12,600 s = 15,120 meters
Therefore, the distance between the two cities is 15,120 meters, which matches option (b).