Based on the fact that the four South African countries act in a way that allows for a common external trade policy, they established a b. Customs Union.
This refers to an organization that comprises of various nations who decide to remove trade barriers with each other.
These nations will trade freely with each other, and will have a common trade policy with other nations outside the Customs Union.
Options for this question are:
a. Officient market.
b. common market.
c. command economy.
d. customs union.
e. free trade area.
Find out more on Customs Unions at https://brainly.com/question/13309526.
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