Some Nations That Seek to Produce All of Their Own

Some nations that seek to produce all of their own needs face the problem that:

A) some industries are too small to be efficient if restricted to their domestic markets alone.
B) they can deplete their natural resources as a result.
C) the opportunity cost of producing some of their own goods is lower than that of trading with others for them.
D) they will not be able to satisfy the wants of all of their citizens.