The passage is mainly about ______。
选项：

A:the Wall Street
B:the stock exchange
C:the stock
D:the stockholder and stockbrokerPassage FiveTom had once worked in a city office in London , but now he is out of work. He had a large family to support ,so he often found himself in difficulty .He often visited Mr. White on Sundays ,told him about his troubles, and asked for two or three pounds.Mr. White, a man with a kind heart, found it difficult to refuse the money, though he himself was poor. Tom had already received more than thirty pounds from Mr. White ,but he always seemed to be in need of some more.One day, after telling Mr. White a long story of his troubles, Tom asked for five pounds.Mr. White had heard this sort of thing before, but he listened patiently to the end. Then he said, “I understand your difficulties, Tom. I'd like to help you. But I'm not going to give you five pounds this time . I'll lend you the money, and you can pay me off next time you see me."Tom took the money, but he never appeared again.