Write a multi-choice question for the following article, with the given choices and answer: Article: In many businesses, computers have largely replaced paperwork, because they are fast, and do not make mistakes. And they are honest. Many banks say that their business is "untouched by human hands" and therefore safe. But they have no thought that the growing number of computer crimes show they can be used to steal. Computer criminals don't use guns. And even if they are caught, it is hard to punish them because there is often no proof. A computer cannot remember who used it. It simply does what it is told. The head teller at a New York City bank used a computer to steal more than one and a half billion dollars in just four years. No one noticed this because he moved the money from one account to another. Each time a customer whose money he had stolen questioned the balance in his account, the teller said it was a computer mistake, then replaced the missing money from someone else's account. This man was caught at last. Some workers use the computer's power to punish their bosses they consider unfair. Recently, a large company fired its computer record assistant for reasons that were connected with her personal life rather than her job. She was given thirty days notice. In those thirty days, she stole all the company's computerized records. Most computer criminals have been common workers. Now police wonder if this is "the tip of iceberg". As one official says, "I have the feeling that there is more crime out there than we are catching. What we are seeing now is all so poorly done. I wonder what the real experts are doing--the ones who really know a computer works." Options: A because no one had questioned him B because he had stolen money carefully C by moving money through computers D by lying to the police Answer: C by moving money through computers Question:
The head teller covered up his crimes _ .