The Bowed-Outward Shape of a PPF

Multiple Choice

The bowed-outward shape of a PPF

A) is due to capital accumulation.
B) reflects the unequal application of technology in production.
C) illustrates the fact that no opportunity cost is incurred for increasing the production of the good measured on the horizontal axis but it is incurred to increase production of the good measured along the vertical axis.
D) is due to the existence of increasing opportunity cost.