13. Top college graduates are having more difficulty demonstrating their superiority to prospective employers than did the top students of twenty years ago when an honors degree was distinction enough. Today’s employers are less impressed with the honors degree. Twenty years ago no more than 10 percent of a given class graduated with honors. Today, however, because of grade inflation, the honors degree goes to more than 50 percent of a graduating class. Therefore, to restore confidence in the degrees they award, colleges must take steps to control grade inflation.

Which one of the following is an assumption that, if true, would support the conclusion in the passage?

(A) Today’s students are not higher achievers than the students of twenty years ago.

(B) Awarding too many honors degrees causes colleges to inflate grades.

(C) Today’s employers rely on honors ranking in making their hiring decisions.

(D) It is not easy for students with low grades to obtain jobs.（A）

(E) Colleges must make employers aware of the criteria used to determine who receives an honors degree.

为什么答案是A呢？这个假设是怎么推出的？