请教结论题

Each increase of 1 percent in real disposable personal income per capita will increase the share of the electorate for an incumbent by about 2.2 percentage points, other things being equal.Since 1952 there has been a decline in real disposable income during only one persidential election year. The incumbent lost that election.

Which of the following conclusions can be properly drawn from the statements above?

a.when an incumbent runs for office, he or she is likely to win.

b.political parties should take care to put forth a candidate who seems prosperous.

c.Presidential candidates should put their greatest efforts into improving their public image.

d.because a presidential campaign requires the expenditure of large amounts of money, it frequently impoverishes a candidate and his or her supporters.

e.the outcome of a presidential elction is substantially affected by factors other than the ideological positions of  the candidates.

答案怎么是E呢？E选项里出现原文没有的新名词啊，为什么E对呢？

死抠规则？

E的意思是：选举结果不仅仅和施政方要相关。

题目说了国民收入增加一个百分点，现任总统的支持度就会增加2.2个百分点。52年国民收入降低，因此当任总统落选。直接结论是选举结果和国民收入有关。

多些和美国选举有关的背景知识，阅读理解搞清楚，题目就容易做了。