求助MANHATTAN的一道逻辑题

wellmichelle

Among those automobile mechanics who own their own garages and completed a qualifying course at Main Street Technical School, 35% earn above $80,000 a year. Among those who own their own garages but did not complete the qualifying course at Main Street Technical School, only 10% earn above $80,000 a year. These figures indicate the importance of technical education in getting a higher salary.

　　The argument above depends on which of the following assumptions about the people mentioned in the statistics?

A.At least one-third of the group of people who did not complete the qualifying course would today be earning more than $80,000 a year if they had completed the course.




B.The group of people who did not complete the qualifying course and the group who did are comparable in terms of factors that determine how much people are paid.




C.Most of those people who did not complete the course did so entirely because of the cost of the course.





D.As a group, those persons who completed the course are more competent as mechanics than the group that did not.







E.The group of people who did not complete the qualifying course and who today earn more than $80,000 a year are more capable than the group that completed the course
为什么答案选B呢？

sisichen666

建议LZ请发到CR专区，NN会有解答。。。。。
思路：假设题用逻辑链+结论+无关信息排除+not weaken检验正确选项