单项选择题

Computer programmer David earns $40,000 a year designing new computer games, yet he cannot find a bank to let him have a credit card. Instead, he has been told to wait another two years until he is 18. The 16-year-old works for a-small firm in Liverpool. David’s firm releases two new games for the fast growing computer market each month.
But David’s biggest headache is what to do with his money. Even though he earns a lot, he cannot drive a car, take out a mortgage(抵押货款), or get credit cards. "I got the job because the people who run the firm knew I had already written some programs." he said. David spends some of his money on records and clothes, and gives his mother 50 pounds a week. "Unfortunately, computing was not part of our studies at school," he said, "but I had been studying it in books and magazines for four years in my spare time. I knew what I wanted to do and never considered staying on at school." David added, "I would like to earn a million and I suppose early retirement is a possibility. You never know when the market might disappear.\
What is one of the problems that David is facing now