下列关于文学名著内容及常识的表述，完全正确的一项是(      )

    I'm Sam. My hobby is playing chess（棋）—one of the greatest games in the world. My mom taught me how to play when I was 7. She beat (打败) me every time for the first year. But then on my eighth birthday, I won for the first time. I nearly always beat her from then on.

    It takes about a day to learn the rules (规则). But if you want to be good, you have to practice for years. You don't need much to play chess—just a chess set (棋具) and someone to play with.

    Chess sets can be quite cheap, or very expensive. Some people collect chess sets as a hobby, but some prefers playing.

    There is a chess club in our school, and we meet every week to play with each other. I'm the best player in the club, and the captain of the school chess team. This year we won the All English Schools' Championship (锦标赛), and I had to go up on stage (台子) in front of the whole school to accept the trophy (奖品).

    I'm saving up my money to buy a chess computer. It's very expensive, but very good for practice. In that way, I'll always have someone to play with. One day I will be the world chess champion (冠军).

下图是三个同等规模商业中心对周围顾客达成交易的概率的等值线分布图。回答下列各题。