请大家帮我看下这一题，谢谢

ShirleyWong

19. In Kravonia, the average salary for jobs requiring a college degree has always been higher than the average salary for jobs that do not require a degree.  Current enrollments in Kravonia’s colleges indicate that over the next four years the percentage of the Kravonian workforce with college degrees will increase dramatically.  Therefore, the average salary for all workers in Kravonia is likely to increase over the next four years.

Which of the following is an assumption on which the argument depends?

A.    Kravonians with more than one college degree earn more, on average, than do Kravonians with only one college degree.
B.    The percentage of Kravonians who attend college in order to earn higher salaries is higher now than it was several years ago.
C.    The higher average salary for jobs requiring a college degree is not due largely to a scarcity among the Kravonian workforce of people with a college degree.
D.    The average salary in Kravonia for jobs that do not require a college degree will not increase over the next four years.
E.    Few members of the Kravonian workforce earned their degrees in other countries.
  Answer: C
虽然我排除了一些选项，但是我不明白C的逻辑，请问谁能帮我解释下C的思路，为什么选C？像C说的，如果市场上不缺有degree的人，那么就算四年内有degree的人增加了，平均工资也不一定会升啊。那C怎么会是假设呢

Serena11457

谈谈个人的理解啊，C的核心就在一个scarcity，即workforce with a college degree的稀少不足，也就是说他们这群人的高工资不是由于大学生劳动力的稀少不足，（推论，而在于大学生劳动力的真实能力），因此next four year尽管大学生劳动力的比例会大幅上升，不会影响其含金量。这就是所需的假设。
如果高工资源于大学生劳动力的稀少性，那么今年（比如）有10个大学生，大家的工资是5000一个月，明年，有1000个大学生，稀少性没有了，大家的工资是50一个月，那么实际上，average salary 是没有变化的。

ShirleyWong

请问像这样的思维过程，在考场上，能很快完成么？

reginechen

我很白的选了D。试着理解C，感觉是排除它因的支持。除非也可以得到，D是有点不相关

WALLMAGE

C选项排除了一个他因，即如果有学历的工人的工资大于无学历的工资是由于有学历的工人稀少导致的。那么增加该种工人的数量就不一定会增加总的平均工资。

vakaka

原文最后说的就是大学文凭数量增加，平均工资增加。D说的是没有大学

文凭的工资不增加，和原文没有什么关系，C说的是工资高和大学文凭数量增

加没有关系，所以C更直接。