Bunuel
Critics fear that the decline in what constitutes a good secondary school education have weakened this country's standing in the world.
A. in what constitutes a good secondary school education have
B. in what constitutes a good secondary school education has
C. in what constituted a good secondary school education has
D. in what constituted a good secondary school education have
E. in constituting a good secondary school education has
In A and D,
have (plural) does not agree with
the decline (singular).
Eliminate A and D.
All verbs should be in the SAME TENSE unless there is a reason to change tense.
C:
Critics fear...the decline in what constituted...has weakenedHere, there is no reason for the red verb to be in the past tense, while the two blue verbs are in forms of the present tense.
Eliminate C.
E:
the decline in constitutingThe phrase above does not convey a clear meaning.
It seems imply that the act of constituting is being performed less successfully or less frequently.
Neither interpretation reflects the intended meaning of the original sentence.
In the original sentence, the intended meaning is that there has been a decline in educational STANDARDS -- that WHAT CONSTITUTES a good education TODAY is of lower quality that what USED to constitute a good education.