[求助]这道题不懂，请教下大家

surveys show that every year only 10 percent of cigarette smokers switch brands. yet the manufacturers have been spending an amount equal to 10 percent of their gross receipts on cigarette promotion in magazines. it follows from these figures that inducing cigarette smokers to switch brands did not pay , and that cigarette companies would have been no worse off economically if they had dropped their advertising.

of the following ,the best criticism of the conclusion that inducing cigarette smokers to switch brands did not pay is that the conclusion is based on

A. computing advertising costs as a percenage of gross receipts, not of overall costs

B.past patterns of smiking and may not carry over to the future

C.the assumption that each smoker is loyal to a single brand of cigarettes at any one time

D. the assumption that each manufacturer produces only one brand of cigarettes

E. figures for the cigarette industry as a whole and may not hold for a particular company

这题的答案是E，不过我还是不明白

我看了好长时间才确认答案是E。说的是每年烟草公司要花10%收入来做广告，同时有10%的吸烟者换牌子，得出结论是完全没必要做广告，相当于10%吸烟者白抽烟没掏钱。为啥呢？因为他是对于烟草行业来说的，有10%的钱给了杂志做广告了，所以相当于这部分收入没有了，如果是针对单独一个公司来讲，因为走了10%，可能因为做广告会再来10%或者更多或更少，总之，这个结论肯定与单独的一个公司是无关的。

A. computing advertising costs as a percenage of gross receipts, not of overall costs

换牌子的smokers没花钱这个结论与成本还是收入无关

B.past patterns of smiking and may not carry over to the future

过去时还是将来时也无关

C.the assumption that each smoker is loyal to a single brand of cigarettes at any one time

人家说的是换了牌子，就没有啥loyal啦

D. the assumption that each manufacturer produces only one brand of cigarettes

几种牌子跟smokers花钱无关

E. figures for the cigarette industry as a whole and may not hold for a particular company

深入浅出，谢谢