Jonathan James looks like just another kid

问题：

Jonathan James looks like just another kid about to graduate from high school. But this 19-year-old Swede is anything but ordinary, from the computer in his parents’ home he helps the US Federal Bureau of Investigation(FBI) find out the world’s most wanted cyber criminals.
Jonathan first made headlines when he and another Swede, Fredrik Bjoerck, found out the maker of the "Melissa" virus in March 1999. He came to the aid of the FBI again on May 7, finding out the suspected sender of the dangerous "I LOVE YOU" virus. The suspect was caught in Manila on May 8.
Jonathan’s special skills are in hot demand as officials around the world express alarm at the "virtual" crimewave. In between studying for final exams, hanging out with friends and refereeing his younger brother’s football matches, the quiet, gentle teenager also gives lessons on e-security to large companies. He reads a lot and exchanges information with other computer experts to know much about the latest tricks of the hacker trade.
Many companies have already tried to employ him, but he is not interested at the moment. Instead, he plans to begin law school in the autumn at Sweden’s Uppsala University and start up his own e-security company.
Although he works with the FBI now, his family insists he’s just "a regular kid". "Jonathan is a great kid, he has his friends and he does a lot more than just play with the computer, " his little sister Tessa said, adding that he helps the FBI because "he likes to help", not because he’s looking for fame and recognition.
When the world was hit by the "Love Bug" virus, Jonathan was too busy preparing a speech on e-security to look into the problem. "Finally on May 7, I had some free time, so I began looking. " Within a few hours, he had found the suspect and e-mailed his method and results to the FBI. He said his work on the "Melissa" virus, which took three weeks to solve, was a big help in finding the suspect so quickly. "This time I knew exactly where to start, I knew what to disregard and what to look at. \

The public started to know something about Jonathan just from ______.

A. his helping the US FBI to find out the sender of the dangerous "I LOVE YOU" virus
B. his work together with Fredrik Bjoerck to find out the maker of the "Melissa" virus
C. his little sister’s talk about his good qualities as a regular kid and a good programmer
D. his speech on e-security to many computer companies after his fight against hackers