I believe the answer is It shows that Charlemagne conquered a huge part of Europe.
Charlemagne became the first man in history to conquer Western Europe since the downfall of the Roman Empire. Eventhough his empire was not as large as the Romans, His achievement still pretty much respected becuase many experts believe that the current France and England is the fragments of what used to be Charlemagne's empire.
Both used the source of coal to run and they both transported needed and wanted materials. The only difference was that the steamboat was obviously by water and the locomotive was by land. Their similar impact was that they both transported wanted and needed goods faster and there was less work needed since it was just individuals working the machines and it made it easier
I think the answer is going to be "C"
