The percentage of students at the college where I teach that

The percentage of students at the college where I teach that have managed to achieve the grade necessary to enter into university has increased since 1998. We may therefore conclude that the entrance standards of the universities have been dropping for the past few years.
Which of the following, if true, would most strengthen the argument above?

A) The percentage of students from all the neighbouring colleges that achieve the grade necessary for university entrance has also increased.

B) The number of students in my college that achieved the entrance grade to university in 1998 was comparatively low.

C) A report issued by the Education Minister claims that the quality of degrees awarded by universities has remained consistently high since the mid 1990s.

D) The standard of education required for students entering the college where I teach has been raised consistently since 1999.

E) Some students have compared the entrance examination for their chosen university this year with the corresponding examination from 1998 and expressed the opinion that the latter was much harder.

Kindly provide some explanations.