再发jj不懂题!!HELP!

In the past, every ten-percentage-point increase in cigarette prices in the country of Coponia has decreased per capita sales of cigarettes by four percent.  Coponia is about to raise taxes on cigarettes by 9 cents per pack.  The average price of cigarettes in Coponia is and has been for more than a year 90 cents per pack.  So the tax hike stands an excellent chance of reducing per capita sales of cigarettes by four percent.
Which of the following is an assumption on which the argument depends?
A.Tobacco companies are unlikely to reduce their profit per pack of cigarettes to avoid an increase in the cost per pack to consumers in Coponia.
B.Previous increases in cigarette prices in Coponia have generally been due to increases in taxes on cigarettes.
C.Any decrease in per capita sales of cigarettes in Coponia will result mainly from an increase in the number of people who quit smoking entirely.
D.At present, the price of a pack of cigarettes in Coponia includes taxes that amount to less than ten percent of the total selling price.
E.The number of people in Coponia who smoke cigarettes has remained relatively constant for the past several years.

i think  the ans is A,is it right? HELP!

A对

这题似乎是哪道GWD

9cents和price90cents，price上升10%，根据题目的说法，销售会将4%

但是这有个前提，那就是price确实会上升10%，如果烟草商会降低价格，使得上升没有10%，那么销量不会降4%

A说，烟草商不会降低利润，那么原先的90cent的price不会改变，这样的话结论才能得出。