Which of the Following Is True of Occupational Licensing Laws

Which of the following is true of occupational licensing laws?

A) Occupational licensing requires that the competency of workers be certified, but no one is prohibited from providing their services in the licensed occupations.
B) Occupational licensing laws reduce competition in some occupations and make it more difficult for new entrants to compete in these labor markets.
C) Occupational licensing has become less common over the past 40 years in the U.S.
D) Occupational licensing is mandated by the Occupational Safety and Health Administration in order to make employment safer for workers.