Which of the following represent differences between a budget constraint and a production possibilities frontier (PPF)?
Select all that apply:
a. the budget constraint is a straight line; the PPF is a bowed out shape
b. the axes of the budget constraint contain specific numbers; the axes of the PPF do not
c. the axes of the budget constraint do not contain specific numbers; the axes of the PPF do
d. there is no difference; the budget constraint and the PPF are the same thing