Opponents of Licensing for Public Relations Practitioners Raise What Constitutional

Opponents of licensing for public relations practitioners raise what Constitutional issue(s) as the major obstacle(s) to state licensing in the United States?

A) Compelling state interest and freedom of expression
B) Freedom of individual choice protected by the Constitution
C) Differences in "public relations" practiced in one state compared to in another
D) Imposition of educational requirements and testing is unconstitutional
E) Tenth Amendment forbids regulation of occupations and admission to practice