题目内容：
根据下列材料，请回答题：Text 3
The way people in the US travel to and from work has changed a lot in the last fifty years．Be．fore the Second World War，most people lived in the town or the city where they worked．Aimost everyone either walked to work or used a good inexpensive transportation system．Many of these systems were electrified and ran on tracks，so they used very little energy．
After 1945，the United States government built many new roads and highways．People moved farther and farther from the cities where they worked because they could drive their cars on these new roads from their suburban(郊区的)homes to work in the city．Some of the big car makers al-so bought the electrified transportafion systems so they could destroy them．As people stopped using public transportation，cities spent less money to fix old buses and trains or to buy new Ones．Public transportation got worse and worse．
In the late l960s，people found out that the increase in the use of cars led to many problems． There were always too many CarS for the highway system，and terrible traffic problems developed．People were spending hours in traffic jams getting to and from work every day．In addition，the air in many cities became dirty because of pollution from millions of CarS，and many people died in traffic accidents．
As people began to get worried about how the use of CarS was hurting the environment，cities began to spend more money on public transportation again SO fewer people would have to drive CarS．
When gas became very expensive in the mid一1970s，the number of people taking pubfic trans．portation began to increase．Because it is terribly expensive to build new public transportation sys．tems，it is very difficult to make big changes in the way people travel，but an increase in the use ofpublic transportation has begun．
Why did some Car companies buy and destroy public transportation systems? A．They were slower than CarS．
B．They were too old to be fixed．
C．They were trying to build better ones．
D．They wanted to sell more of their products．
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