There was an engineer who had an exceptional gift for fixing all mechanical （机械的) thing

There was an engineer who had an exceptional gift for fixing all mechanical (机械的) things. After serving his company heart and soul for over 25 years, he happily retired(退休). Several years later his company telephoned him regarding a seemingly impossible problem they were having with one of their multi-million-dollar machines. They had tried everything and everyone else to get the machine fixed, but no help.

In desperation (绝望), they called on the retired engineer who had solved so many of their problems in the past. The engineer unwillingly took the challenge. He spent a day studying the huge machine. At the end of the day he marked a small X in chalk on a particular part of the machine and proudly stated, "This is where your problem is.” Tile part was replaced and the machine worked perfectly again.

The company received a bill for $ 20,001 from the engineer for his service. They told him to make a list of his charges.

The engineer answered briefly:

One chalk mark... $ 1

Knowing where to put it... $ 20,000.

The engineer retired ______.

A．after he worked in the same company for less than 25 years

B．after he worked in different companies for 25 years

C．after he worked faithfully in the same company for over 25 years

D．after he worked heart and soul in his own company for 25 years