Why does north korea not make as much money as south korea

In which research method does a researcher change the value of one variable to determine how the change affects another variable? a. experiment b. observational research c. survey d. case study

How has the elimination of trade barriers affected the movement of goods among member countries of the european union? a. member countries are able to produce all the goods they need. b. goods can move freely among member countries. c. member countries no longer need to trade with countries outside the eu. d. larger countries are able to import more goods than smaller ones.

Which argument for religious reform might be convincing to a priest, pope, or king?