What Are the Biggest Advantages the U

What are the biggest advantages the U.S. has over the EU in terms of being an Optimum Currency Area?

A) low mobility of labor, higher labor productivity, lower level of intra-regional trade
B) high unionization of U.S. labor force
C) high mobility of labor force, more transfer payments between regions
D) higher uniformity of population's taste in consumption
E) more specialized labor force and natural resource advantages