单选题 The inflation index for the year 1989 relative to the year 1970 was 3.56, indicating that, on the average, for each dollar spent in 1970 for goods, $3.56 had to be spent for the same goods in 1989. If the price of a Model K mixer increased precisely according to the inflation index, what was the price of the mixer in 1970?
(1)The price of the Model K mixer was $102.40 more in 1989 than in 1970.
(2)The price of the Model K mixer was $142.40 in 1989.

A、条件(1)充分，但条件(2)不充分．
B、条件(2)充分，但条件(1)不充分．
C、条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．
D、条件(1)充分，条件(2)也充分．
E、 (E) 条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．

【正确答案】 D

【答案解析】[解析] 设该搅拌器在1970年的价格为x美元，根据(1)x+102.4=3.56x可以求出x=40美元；根据(2)得x=142.40÷3.56=40美元。