In the following question, out of the four alternatives, select the alternative which best expresses the meaning of the idiom/phrase.
A fool's paradise
A fool's paradise means a dreamland of a person who doesn't know about the existence of the dreams made by him/her.
e.g. You're living a fool's paradise if you think that you can settle down in America within a few days.
Therefore, option 3 is the correct answer.