The Bowed Out (Concave)shape of the Production Possibilities Curve Implies

The bowed out (concave) shape of the production possibilities curve implies that as production of one good

A) increases, society must forgo increasing amounts of another good.
B) increases, society must forgo decreasing amounts of another good.
C) decreases, production of other goods decreases as well.
D) increases, production of other goods increases as well.
E) increases, society can obtain a free lunch.