If Counyty A forms a customs union with Country B, then____________
A.
goods exported from Country A to Country B continues to face tariff by Country
B.
all new trade between Country A and Country B because of the union is known as " trade creation."
C.
all trading partners of countries A and B must necessarily benefit from the customs union.
D.
Countries A and B may especially benefit from the union if substantial economies of scale exist in some of the A and B industries.