Which Statement Is NOT One of the Four Principles of Individual

Multiple Choice

Which statement is NOT one of the four principles of individual choice?

A) Choices are necessary because resources are scarce.
B) Unpaid volunteer work is irrational since economic rationality dictates that individuals should only engage in work they are paid for.
C) The true cost of something is its opportunity cost.
D) "How much" is a decision at the margin.