问题如下：
Consider three products A B C in the market. If the price of Product A is increased by 3%, the quantity of demand for Product B will decrease by 2.8% and the quantity of demand for Product C will increase by 1.4%. Which of the conclusion below is least appropriate?
选项：
A. Products A and B are complements.
B. Products A and C are substitutes.
C. Products B and C are complements.
解释：
C is correct. If an increase in price of one good increases the demand for the other, these two goods are substitutes (A and C, tea and wine). If an increase in price of one good decreases the demand for the other, these two goods are complements (A and B, tea and teapot). We cannot conclude that B and C are complements, teapot and wine are not complements.
考点：替代品和互补品
解析：
如果一种商品的价格上涨增加了对另一种商品的需求，这两种商品就是替代品(A和C，茶和酒)。如果一种商品的价格上涨降低了另一种商品的需求，这两种商品就是互补品(A和B，茶和茶壶)。我们不能断定B和C是互补的，茶壶和酒不是互补的。
这题如果用价格弹性的公式算，两个比值都是正值啊
