一道PREP -2 数学题的题干理解

feiya

A certain group of car dealerships agreed to donate x dollars to a Red Cross chapter for each car sold during a 30-day period. What was the total amount that was expected to be donated?
1) A total of 500 cars were expected to be sold.
2) 60 more cars were sold than expected, so that the total amount actually donated was $28,000.

我选了E。因为我认为题干中提到了during a 30-day period,而（1）虽然说期望500辆车被卖掉，但是没有说这500辆车就是在这30天内卖掉的。

可是正确答案是C。迷惑了。。。大家帮我分析分析。。。