Which of the Following Are the Economic Forces Underlying the International

Which of the following are the economic forces underlying the international flow of goods and services?

A) Productive factors move from nations where they are scarce to nations where they are abundant.
B) Productive factors flow in response to differences in returns when they are less than the costs of moving from one country to another.
C) Productive factors move for reasons that are significantly different from those economic forces that explain the international movement flow of goods and services.
D) Productive factors move from where they are abundant to where they are scarce.