question_answer

A sentence with an underlined idiomatic expression is given. What is the meaning of the idiomatic expression 'To build castles in the air' in the sentence given below ?

Don't build castles in the air. just find some work to ' earn money.

A) to make the most beautiful plans that always come true

B) to make the most practical and fruitful plans that never fail

C) to daydream or to make plans that can never come true

D) None of the above