In Comparing the European Union and the United States as OCAs

In comparing the European Union and the United States as OCAs, the authors of the text conclude that there is(are) :

A) greater integration of goods markets and greater labor mobility in the United States than in Europe, but about the same symmetry of shocks in the two regions.
B) greater integration of goods markets, greater labor mobility, and greater symmetry of shocks in the United States than in Europe.
C) less integration of goods markets, but greater labor mobility and greater symmetry of shocks in the United States than in Europe.
D) greater integration of goods markets, greater labor mobility, and greater symmetry of shocks in Europe than in the United States.