US Union Membership Has Declined Substantially in Recent Years

Multiple Choice

U.S. union membership has declined substantially in recent years. Which of the following is not usually cited as a causal factor?

A) Most nonunion workers are in manufacturing industries.
B) Import competition has reduced or restrained the growth of employment in some highly unionized industries.
C) Some industries and firms have migrated to the less-unionized South.
D) Managerial opposition to unions has intensified.