In Which of the Following Instances Does Decentralization of Production

In which of the following instances does decentralization of production make most sense?

A) The product serves universal needs.
B) The production technology has low fixed costs and low minimum efficient scale,and flexible manufacturing technology is not available.
C) Important exchange rates are expected to remain relatively stable.
D) Differences between countries in factor costs have a substantial impact on the costs of manufacturing in various countries.