题目选项分析

In the year 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.

Which of the following, if true, would most strengthen the argument above?

【选项】Most consumers were unaware that the tax on cigarettes was going to increase.