I think the answer is D, the radiative zone because, energy generated by nuclear fusion in the core moves outward as electromagnetic radiation. in other words, Energy is in the core but it takes radioactive waves to make it reach earth.
I don't think it's A, B C, because,
the corona has to do with the light of the sun
gamma zone is an example of radiation
the core is the base of the energy, where it's all stored
radiative zone makes it reach earth
That would be the choice I would choose. I hope this helps you.