Diminishing Returns to Specialization Occur When

Diminishing returns to specialization occur when

A) resources can move freely from the production of one good to another within a country.
B) more units of resources are required to produce each additional unit.
C) the cost of producing goods reduces substantially with increase in number of goods produced.
D) the quality of resources comes down as a result of producing more goods.
E) the quality of goods produced per unit of resource begins to improve.