The correct answer is D) They can only raise money from their members.
A limit on the way political action committees can raise money when
they are branches of labor unions or professional organizations is that they can only raise money from their members.
This is the correct kind of regulation to maintain the proper control of labor unions or professional organizations. Just their members can contribute with money for the political campaign. They are the ones interested in their own agendas and have their own interests at hand.