Economic Problems
Whenever a choice is made by someone, it involves opportunity cost, which is the next best alternative forgone in the process of choice making.
Something isn't free if it has an opportunity cost attached to it.
"There is no such thing as a free lunch"
Free good include water, air, and sunlight
3 questions of Choice Making :-
To answer these questions countries come up with various solutions : Planned, Mixed and Free economies
Difference between microeconomics and macroeconomics