The point is that choices A, B, and C are fragments without a working verb for the subject; D is the correct one because it uses the right tense of the verb ‘has been’,
for an event that began four decides ago, and that continues.
The present perfect is strongly indicated by the prepositional phrase ‘for four decades’
Any allusion to Keynesians in the modifier clause started by the pronoun who
, should be simply ignored as irrelevant to the main intent of the topic.
E (Incidentally there is a typo and it should be ‘one’ and not ‘on’) is good enough for grammar, but it is not clear what the prepositional modifier ‘for four decades’ is modifying. It wrongly seems to fall on the science rather than domination. Hence, E can be dropped
D remains the preferred choice.
Get the best GMAT Prep Resources with GMAT Club Premium Membership