Final answer:
You must obey a policeman over stop signs and flashing red lights because police officers have authority to direct traffic which can override other traffic control devices.
Step-by-step explanation:
The question is asking which of the following you must obey over the others: a policeman, a stop sign, or a flashing red light. Police officers should be obeyed over stop signs and flashing red lights in traffic situations. This is because a policeman has the authority to direct traffic and override static traffic control devices such as stop signs or flashing red lights. Traffic signs and signals are static forms of authority that provide a regular system for traffic flow, but a police officer can make dynamic decisions based on current road conditions or emergencies. In a situation where a police officer is directing traffic, you are required to follow the officer's instructions even if they contradict the stop sign or flashing red light.