The Standard Model of Geographic Migration Suggests

The standard model of geographic migration suggests:

A) Migration occurs when there is a good chance that a worker will gain back his costs of moving.
B) Increases in migration costs reduces the gains to migration.
C) Improvements in economic opportunities in the current region of residence discourage migration.
D) Improvements in economic opportunities in a possible region of residence encourage migration.
E) All of the above statements are true.