At three a.m., Jack Mills was sitting at the controls of the mail train. The train was made up of 13 cars. At the end of the train, 71 mailmen sat sorting the mails. Inside the second car, there were only five mailmen and 128 bags full of five-pound notes. This train had run more than 100 years without being robbed. At three minutes past three, Mills and his helper, David Whitby, saw a yellow warning light. They slowed the train, and then stopped. Whitby went to the telephone beside the track. It was out of order. Then he saw a man moving between the second and the third cars. Before Whitby could give a warning, he was knocked down by two men. Mills' cars with all the mailmen had been disconnected by the robbers. At the bridge, the bags of money were unloaded from the train and thrown into waiting trucks. One of the robbers who obviously knew the schedules of all the trains kept looking at his watch. At 3:45 he said, "That will have to be enough." The robbers drove away with more than 2,500,000 pounds. The robbers   _   before the train stopped.
were all in the train forced Mills to stop the train were waiting for the train to stop ordered Mills to go on driving
Question: At three a.m., Jack Mills was sitting at the controls of the mail train. The train was made up of 13 cars. At the end of the train, 71 mailmen sat sorting the mails. Inside the second car, there were only five mailmen and 128 bags full of five-pound notes. This train had run more than 100 years without being robbed. At three minutes past three, Mills and his helper, David Whitby, saw a yellow warning light. They slowed the train, and then stopped. Whitby went to the telephone beside the track. It was out of order. Then he saw a man moving between the second and the third cars. Before Whitby could give a warning, he was knocked down by two men. Mills' cars with all the mailmen had been disconnected by the robbers. At the bridge, the bags of money were unloaded from the train and thrown into waiting trucks. One of the robbers who obviously knew the schedules of all the trains kept looking at his watch. At 3:45 he said, "That will have to be enough." The robbers drove away with more than 2,500,000 pounds. The robbers   _   before the train stopped.
A. were all in the train
B. forced Mills to stop the train
C. were waiting for the train to stop
D. ordered Mills to go on driving
Answer: