The answer should be A, "Communism promised jobs after the insecurities of war." Hope this helps!
The subject of science is very broad. With that being said, I think there is no official regulatory board that decides the branches of science. Scientific developments are products of joined efforts of different scientists. These scientists could rebuke another's work provided there is evidence. As long as the theory is generally accepted by the scientists and no one rebukes it effectively, then it is a generally accepted fact and everyone adapts it.
Hence, the answer is B.
the sun/radiation (sorta)/ fusion/(yea pretty much the sun)
