Understanding the argument -
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. - Background Info.
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. - Background Info.
Today, however, because of grade inflation, the honors degree goes to more than 50 percent of a graduating class. - Contrast and reason/cause of the contrast.
Therefore, to restore confidence in the degrees they award, colleges must take steps to control grade inflation. - Conclusion. This states the minimum or necessary condition "must take steps to control grade inflation" to achieve the goal, which is to "restore confidence in the degrees they award."
Which one of the following is an assumption that, if true, would support the conclusion in the passage?
The assumption is that there is no alternate cause for a higher percentage of honors degrees, and containing that cause will help.
(A) Today’s students are not higher achievers than the students of twenty years ago. - There is no alternate cause. If we negate it, it means there is an alternate cause, and then the minimum condition established in the argument is shattered. Ok.
(B) Awarding too many honors degrees causes colleges to inflate grades. - What causes it to be out of scope?
(C) Today’s employers rely on honors ranking in making their hiring decisions. - The core of the argument is X causes Y. Remove X, and the effect will be contained. Whether employers rely on it or not is irrelevant. Even if they don't rely on it, taking care of grade inflation could still contain the percentage of honors and thus restore confidence. Out of scope.
(D) It is not easy for students with low grades to obtain jobs. - out of scope.
(E) Colleges must make employers aware of the criteria used to determine who receives an honors degree - out of scope.