Which Statement Best Describes International Comparisons of Unionization Rates

Which statement best describes international comparisons of unionization rates?

A) Private sector unionization is about the same (around 20%) in all developed countries.
B) Private sector unionization is greater in less-developed countries than in developed countries.
C) Private sector unionization rates have fallen significantly in all developed countries over the last 40 years.
D) Private sector unionization rates vary greatly by country.
E) Private sector unionization rates exceed public sector unionization rates in all developed countries.