Concept:Speed is distance divided by time.Convert distance from km to metres and time from hours to seconds.Explanation:Distance is 720 km.In metres, 720 km =720×1000=720000 m.Time is 8 hours.In seconds, 8 hours =8×60×60=28800 s.Speed =28800720000 m/s.Cancel zeros: 28800720000=2887200=25 m/s.Answer:25 m/s, which is option A.