【单选题】A good measure of a country's level of economic integration with a currency area is
A.
the intersection of DD and GG.
B.
the country's price level.
C.
the compatibility of economic policies.
D.
the intersection of AA and GG.
E.
the extent of trade between the joining country and the currency area and the ease with which labor and capital can migrate between the joining country and the currency area.