單項選擇題
In 1980, the cost ofp pounds of pottoes ws d dollrs. In 1990, the cost of 2p pounds ofIn 1
980, the cost ofp pounds of pottoes ws d dollrs. In 1990, the cost of 2p pounds of pottoes ws d/2 dollrs. By wht percent did the price of pottoes decrese from 1980 to 1990 25% B.50% C.75% D.100% E.400%A.25%B.50%C.75%D.100%E.400%