A、Because they were driven by steam power. B、Because they did the work animals used to do. C、Because they pulled cars full of co

In the early days of railroads horses pulled the trains. The trains had no engines and no power of their own. Richard Traversic of England invented a steam-powered engine in 1840. Soon people were building railroads and steam engines all over the world. [16]Because the steam engine did the work that used to be done by animals, people called them "Iron Horses". Peter Copper was a rich American businessman. He owned a lot of land near the Bottom Hal and Ohio railroad. He wanted the railroad to be successful. He built his own steam engine to drive along the railroad. Most people traveled in coaches drawn by horses. A coach line challenged Peter Copper to a race.
    The day of the race came. At first, the horse was winning the race. Peter Copper’s engine needed time to build up steam. He worked hard to make the train go faster. Soon, he was catching up with the horse. He was going to win the race. Suddenly, one of the parts of the engine broke. The train stopped. The horse rushed ahead. Peter Copper lost the race. Of course, that is not the end of the story. By 1870, railroads extended all across the United States. The Iron Horse had become an important part of American life.
16. Why did people call steam engines Iron Horses?
17. Why did Peter Copper build his own steam engine?
18. How did Peter Copper lose the race?