I go for A.
A: the tense used "past perfect" in the sentence best describes the action (develop and enforce), which has started in the past and still continues to the present.
B: 1st: the simple past tense used is wrong 2nd: necessary for is not idiomatic, rather necessary + infinitive "to" should be used. 3rd: the word "being" is not preferred in GMAT.
C: wrong tense used, and "was to be necessary" awkward and unidiomatic
D: wrong tense used
E: wrong tense used
So why past perfect? the indicator is the "a century of" and the time indicated before that.
Or POE method:
And it is definitely not logical to use either "present" or "future" tense. So D, E are out.
Then, B & C are out because of the unidiomatic use as I mentioned before.
Don't forget Kudo if you like my answer