How Do Professional Associations Differ from Trade Associations

How do professional associations differ from trade associations?

A) Professional associations are based on voluntary membership, whereas trade associations require certain workers to join their organizations.
B) Professional associations are created by acts of Congress; trade associations are created by state legislation.
C) Only professional associations are headquartered in Washington, D.C.
D) Professional associations are more costly than trade associations.
E) Professional associations often have the authority to impose formal discipline on their members.