单项选择题
In the 1880’s, Engineer Herman Hollerith was given a job by the American government to make an official count of the country’s total population, which is now called census. Mr. Hollerith worked hard to search for a way to record the census information of America, and found it on a train, where he saw a conductor using some tool to make holes in tickets. The position of each hole told something about the ticket holder (持有人) , such as hair or eye color. If the "passenger’ turned out to be a train robber, this record would help the pollce catch the criminal. What he saw on the train greatly inspired him to invent a machine which could calculate like an abacus. Hollerith designed punched (打过孔的) cards for an electric computering machine, for each hole gave the answer to a question, and the machine counted the holes. Thus, the great grandfather of the modern computer was born.
This passage mainly discusses how (). A．Hollerith got an idea for an invention
B．train conductors were in charge of recording cencus information
C．Hollerith was hired by a government office
D．train robbers were caught by the police