What reactions occur within a star in stellar equilibrium

Cand d are correct because the rest are just showing your mistakes and you don’t want people who are reading a summary you wrote to see all the mistakes you made.

This is the most closely resembles the model. 

It might. it might because if you think about if they discovered if we came from (lets say something funny like aliens) and thy found cells that matched and they would have t do more research about it but would most probably change their theory.