急，马上要考试了，望牛牛们帮帮忙

sasha_wen

In the years following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent. In contrast, in the year prior to the tax increase, sales had fallen one percent. The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.

The argument above requires which of the following assumptions?
A.During the year following the tax increase, the pretax price of a pack of cigarettes did not increase by as much as it had during the year prior to the tax increase.
B.The one percent fall in cigarette sales in the year prior to tax increases was due to a smaller tax increase.
C.The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase.
D. For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year.
E.As the after-tax price of a pack of cigarettes rises, the pretax price also rises.
参悟不了，答案为什么是D？？？望牛牛指导！

sdcar2010

It is a math question. The total sales = price of a single pack * number of packs sold.

When the sales is down, it could be caused by either the price drop or decrease in number of packs sold.

D makes sure the former did not happen, thus keeps the argument alive.

cycyang

精辟！

那么如何从C得出价格没有降低呢？

cycyang

错了，是D

cycyang

明白了，这里的"cent"是货币单位，不是百分比"percent"：）