逻辑十套中的一道题目

yiwenxjoy

有点迷糊了。
13.Excluding purchases by businesses， the average amount spent on a factory-new car has risen 30 per- cent in the last five years. In the average household budget， the proportion spent on car purchases has remained unchanged in that period. Therefore the average household budget must have increased by 30 percent over the last five years.Which of the following is an assumption on which the argument relies？

   （A）The average number of factory-new cars pur-chased per household has remained unchanged over the last five years.

   （B）The average amount spent per car by businesses buying factory-new cars has risen 30 percent in the last five years.

   （C）The proportion of the average household budgetspent on all car-related expenses has remained unchanged over the last five years.

   （D）The proportion of the average household budget spent on food and housing has remained unchanged over the last five years.

   （E）The total amount spent nationwide on factory- new cars has increased by 30 percent over the last five years.

其实几个选项我都有点疑问。最后我选的是E，答案是A。有大侠解释一下么？

lbchency

GRE现在已经不考逻辑了吧？