being given/ given

Hallo everybody. :)

When dealing with my exercise, I encountered one question. :) May I ask you this now, please? :)

________the opportunity, he might well have become an outstanding cartoonist
A. being given
B. to give
C. giving
D. given

The key is D but could you tell me why not A, please? Please help me out. :) Any help would be greatly appreciated. :)

It is referring to the past, so why would you want to use 'being'. The meaning is If he had been given the opportunity.