Nara has gone to three movies this week.She has some extra money,so she decides to go to another.Which economic principle does this statement BEST represent?

A) Choices are necessary because resources are scarce.
B) The true cost of something is its opportunity cost.
C) "How much" is a decision at the margin.
D) There are gains from trade.

Economic Principle

A widely accepted theory or law that underpins the analysis of economic behaviors and decision-making.

Extra Money

Additional funds or income that surpasses one's regular or expected amount, possibly available for discretionary spending or saving.

Movies

Filmed entertainment viewed by audiences in theaters or through various digital platforms, encompassing a wide range of genres and styles.