In a Production-Possibilities/indifference Curve Diagram Depicting the Movement of a Country

Multiple Choice

In a production-possibilities/indifference curve diagram depicting the movement of a Country from a situation of a uniform tariff against all trading partners to a situation of a Customs union with one trading partner,

A) the country must necessarily move to a higher indifference curve after the formation Of the customs union.
B) the country must necessarily move to a lower indifference curve after the formation of The customs union.
C) home production of the country's export good will increase and home production of The country's import good will also increase after the formation of the customs Union.
D) home production of the country's export good will increase and home production of The country's import good will decrease after the formation of the customs union.