题目

Today there are 6.4 billion people on the earth. By the year 2050, there may be 12.5 billion. There are a lot of people to feed. We need more and more food.One way to produce more food is growing strong­er plants. For thousands of years, farmers have made plants better. Every season, they pick the best plants for the next season. But it works very slowly. Since 1983, scientists have been able to change plants more quickly by changing their genetic(遗传的) material. Foods from plants grown in this way are called genetically modified(改变的) foods, or GM foods.By changing the genetic mate15．点A（a，b），B（a-2，c）两点均在函数y=$\frac{1}{x}$的图象上，且a＞2，则b与c的大小关系为（　　）A．b＞cB．b=cC．b＜cD．不能确定