For the Past Several Decades, Union Membership in the United

For the past several decades, union membership in the United States has been declining. What has been happening in the rest of the world?

A) Union membership has been increasing in almost every other country.
B) In almost every other nation, union membership has held constant.
C) In most cases, union membership in other nations has also been falling.
D) We do not know because other nations do not keep these statistics.