Answer:
a. increasing opportunity costs as more and more of one good is produced
Explanation:
A production possibility frontier is a curve that shows the two combinations of goods an economy can produce given that its resocurces are fully employed.
The production possibility curves is bowed outwards because of increasing opportunity costs as more and more of one good is produced.
If more of one good is to be produced, more of the second good would be given up to increase the production of the first good.
The attached image is the graph of a production possibility frontier. At point A, the maximum amount of good X is produced with zero quantity of good Y. To increase production of good Y and move to point B, some quantities of good X would be given up. To further increase the production of good Y and move to point C, even more quantities of good X would be given up.
I hope my answer helps you
