阅读下面的短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。
A
A young girl and a man were recently found murdered in a parked car in a Boston suburb. The police found no sign in the car. Then they found a witness who had seen a car pass by the murdered couple's car. His description placed the car as a 1950 or 1951 Chevrolet.
Ordinarily, searching through the files for owners of elderly Chevrolets would have been an impossible difficult task because there were two and a half million such cars. In this case, however, the police had a powerful tool—the computer.
The Boston Registry of Motor Vehicles programmed its computer to screen all 1950 and 1951 Chevrolets within a fifteenmile radius(半径)of the suburb—the area in which the police believed the murderer was most likely to be found. Within minutes, the computer uncovered one thousand of wanted cars. A few hours of hand screening turned up a 1950 Chevrolet owner who lived close to the scene of the crime(犯罪)and who had received many traffic tickets. He was among the first suspects(嫌疑犯)to be investigated,_and signs connecting him with the murdered couple were found. He was arrested, and is now waiting for trial.
It can be learned from the text that________.

A．the murderer's car hit the couple's car but did not stop

B．the murderer was last found with the help of a Chevrolet owner

C．the police would not have found the suspect so soon but for the witness

D．searching through the files of Chevrolets owners was impossibly difficult

The underlined word“investigated”is closest in meaning to“________”．

A．questioned

B．supposed

C．determined

D．discovered

Which of the following is true according to the passage?

A．The suspect had often broken the traffic rules before he was caught.

B．One of the police officers saw what the suspect did to the couple.

C．At least 1950 cars were searched in order to find the suspect.

D．The description of the witness turned out to be a lie.

The best title for this passage would be________.

A．Crime—A Problem in the West

B．Chevrolet—A Type of an Old Car

C．Police—A Force in Catching the Murderer

D．Computer—A Help in Fighting against Crime