How do we describe an idealistic person?

The correct answer is: Someone who believes that the world should be a better place

An idealistic person is someone who envisions high goals/visions which might not always be realistic. Here, option A of merely having a lot of ideas do not guarantee all might be unrealistic and option B of being educated is not unrealistic. But option C of wanting the world to be a better place tends to be unrealistic as the thought is very subjective from person to person. so the option Is C.