prep1-75 da niu zhi jiao

wakesleep2011

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?
A. During the second year after the tax increase, cigarette sales increased by a significant amount.
B. The information available to consumers on the health risks of smoking remained largely unchanged in the period before and after the tax increase.
C. Most consumers were unaware that the tax on cigarettes was going to increase.
D. During the year following the cigarette tax increase, many consumers had less income, in inflation-adjusted dollars, than they had had in the previous year.
E. During the year after the tax increase, there was a greater variety of cigarettes on the market than there had been during the previous year.

who can tell me that why C is wrong? Thanks

pygmysog

c is irrelevant.

The conclusion is " The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes"

The key elements here is "tax" and "volumn", you should try to find out the relationship between them.

It doesn't matter whether the consumers were aware of the tax.

lianlianchen

which one is right?

MarsTOF

选C吧？排除一个他因。。

鸢尾花的叶

答案是B，我想问为什么不选C呢？我的理解是“人们意识不到税涨了，说明销售量不受税的影响，说明销售量受税后价的影响，加强。”

为什么不对呢？

ss27

B是最明显的排除他因，就是控制变量。c的话，消费者没有意识到税涨了，但他们会意识到价格涨了。与原文不是很相关。

billxxyy

做了很多题，发现当一眼看不出答案的情况下，取非是比较合适的，本题b取非的话说明有其他变量变动了，结论自然就会被weaken。这样的话b就比较有道理了。