Cars are an important part of life in the United States. Without a car most people feel that they are poor. And even if a person is poor , he doesn't feel really poor when he has a car. Henry Ford was the man who first started making cars in large numbers. He probably didn't know how much the car was going to change American culture. The car made the United States a nation on wheels. And it helped make the United States what it is today. There are three main reasons why the car became so popular in the United States. First of all, the country is a big one and Americans like to move around it. The car makes the travel the most comfortable and cheapest. With a car people can go to any place without spending a lot of money. The second reason cars are popular is the fact that the United States never really developed a practical and cheap public travel system. Long distance trains have never been as common in the United States as they are in other parts of the world. Now there is a good system of air-service provided by planes. But it is too expensive to be used often. The third reason is the most important one, though. The American spirit of independence is what really made cars popular. Americans don't like waiting for a bus, or a train or even a plane. They don't like to have to follow an exact timetable. A car gives them the freedom to plan their own time. And this is the freedom that Americans want most to have. Less oil has caused a big problem for Americans. But the answer will not be a bigger system of public transportation. The real answer will have to be a new kind of car, one that does not use so much oil. In the writer's opinion, cars are popular in the United States mainly because   _  .
Americans like to plan their own time The United States does not have enough public transportation Americans will not feel poor when they travel in their cars Americans cannot move around without their own cars