A Customs Union Is an Organization of Nations Whose Members

A customs union is an organization of nations whose members:

A) have impenetrable trade barriers among themselves but impose no trade barriers on nonmembers.
B) have no trade barriers among themselves but impose common trade barriers on nonmembers.
C) have no trade barriers among themselves but each member country chooses its own trade policies toward nonmember countries.
D) retaliate each other by raising reciprocal tariffs.
E) neither have trade barriers among themselves nor impose any restriction on the nonmember countries.