题目

阅读下面短文，从每小题所给的A、B、C三个选项中，选出一个最佳选项。Many kids do housework such as doing the dishes，making the bed，and folding the clothes.In exchange，they get some money or other computer time.Paying kids for housework is one of the most popular topics，especially at a time when everyone is more careful about money.Some parents think since adults are paid to do their jobs，we should pay kids for everyday housework.But some people don't think kids should get rewards (报酬) for doing housework.Susie Walton，an expert，believe that by rewar设直线y=ax+b与双曲线3x2-y2=1交于A、B，且以AB为直径的圆过原点，求点P（a，b）的轨迹方程．