Final answer:
After departing from Class C or B airspace, you should contact departure control.
Step-by-step explanation:
After departure from the primary airport in Class C or B airspace, contact departure control.
Class C and B airspace are two types of controlled airspace in the United States. Class C airspace is typically found around busy airports and requires radio communication with air traffic control. Class B airspace is even more restrictive and requires both radio communication and clearance from air traffic control.
Contacting departure control after departure ensures that you are in communication with air traffic control and following their instructions for navigation and traffic separation.