Final answer:
The nearest air traffic control unit is normally responsible for broadcasting a MAYDAY Relay during a distress incident.
Step-by-step explanation:
The correct answer is B. The nearest air traffic control unit.
During a distress incident, the responsibility to broadcast a MAYDAY Relay falls on the nearest air traffic control unit. The pilot of the aircraft in distress may also transmit the distress message, but it is primarily the responsibility of the air traffic control unit to coordinate and disseminate the distress call to other relevant parties, such as search and rescue teams.
For example, if an aircraft experiences a distress situation, the pilot should contact the nearest air traffic control unit through radio or other means and inform them about the situation. The air traffic control unit will then take the necessary actions, including broadcasting a MAYDAY Relay to alert other aircraft in the area and initiate a response to assist the aircraft in distress.