Question

9. Which of the following statement(s) about production possibilities frontiers (PPFs) is (are) generally true? 1) the changing slope of the PPF illustrates the concept of increasing costs II) the second derivative of the PPF illustrates the concept of scarcity of resources III) the slope of the PPF illustrates the concept of opportunity costs A) only I B) only II C) only III DI & II E) I & III F) II & III G) I, II & III H) none of the three