Which of the Following Statements Is Correct

Multiple Choice

Which of the following statements is correct?

A) A tradeoff is a limit that forces an exchange or a substitution of one thing for something else.
B) Any point on or within the PPF is production efficient.
C) If capital is idle,the economy is producing at its full potential.
D) The production possibilities frontier shows that there are no limits to production.
E) None of the above answers is correct.