Final answer:
As of 2014, all 50 states, the District of Columbia, Puerto Rico, and Guam had some form of professional regulation.
Step-by-step explanation:
a. All 50 states, the District of Columbia, Puerto Rico, and Guam had some form of regulation.
As stated in Article IV Section 3, the federal government has the power to determine how to handle territories such as Puerto Rico and Guam. The federal government is also responsible for creating and enforcing laws that regulate public safety and general welfare. Therefore, as of 2014, all 50 states, the District of Columbia, Puerto Rico, and Guam had some form of professional regulation.