According to the passage, ______.
A. American automobile industry slowed down its employment of staff since 1900
B．five dollars a day for the blue collar worker was quite a decent wage at the beginning of the century
C．every car produced will enable the manufacturers to have a profit of ＄100,000
D．Ford, GM andChrysler, the only existing motor manufacturers in U.S. have a business of ＄ 200 billion annually