Production possibilities frontiers usually curve out and away from the origin. The implication of this curvature is that: a. the opportunity cost of producing a good stays the same regardless of how much of that good is produced.

b. the opportunity cost of producing a good goes down as more of that good is produced.

c. some resources are better at producing one good while other resources are better at producing alternative goods.

d. technological change is present.

e. as resources are used to produce one good, fewer resources are available to produce another good.