【正确答案】 D

【答案解析】[听力原文] A Russian's hacking of a U.S. bank in 1994 may have been the first online bank robbery. No mask, no note, no gun—this was bank robbery for the technological age. In July 1994, several corporate bank customers discovered that a total of $400,000 was missing from their accounts. Once bank officials realized the problem, they immediately contacted the FBI. Hackers had apparently targeted the institution's cash management computer system, which allowed corporate clients to move funds from their own accounts into other banks around the world. The criminals gained access by exploiting the telecommunications network and compromising valid user IDs and passwords. Working with the bank, FBI began monitoring the accounts for more illegal transfers. They eventually identified approximately 40 illegal transactions mostly going to overseas bank accounts and ultimately adding up to more than $10 million. Meanwhile, the bank was able to get the overseas accounts frozen so no additional money could be withdrawn. The only location where money was actually transferred within the U.S. was San Francisco. Investigators identified the owners as a Russian couple who had previously lived in the country. When the wife flew into San Francisco and attempted to withdraw funds from one of the accounts, the FBI arrested her and, soon after, her husband. Both cooperated in the investigation, telling FBI that the hacking operation was based inside a St. Petersburg computer firm and that they were working for a Russian named Vladimir Levin. In March 1995, Levin was lured to London and was arrested. Why did the bank officials contact the FBI?