Moe Divides His Time Between Studying Physics and Studying Economics

Multiple Choice

Moe divides his time between studying Physics and studying Economics.He has discovered that he can earn grades as shown on this production possibilities curve.
Refer to the figure above.Moe's PPC is bowed out because:

A) he is better at physics than at economics.
B) his studying is subject to the principle of increasing opportunity costs.
C) he is better at economics than at physics.
D) he has failed to take advantage of his comparative advantage.