Final answer:
A police officer is the only one who has the authority to overrule a traffic signal, with the purpose of maintaining safety and proper traffic flow.
Step-by-step explanation:
The question asks who can over-rule a traffic signal. In the context of lawful authority and road safety, a police officer is the only individual among the options provided who has the authority to overrule a traffic signal. This is because police officers are tasked with ensuring public safety and are empowered to direct traffic if needed. Pedestrians, cyclists, and motorists do not have the authority to override traffic signals and must abide by them to ensure safety for all road users.
Multiple reasons justify the presence of a traffic signal at busy intersections. For instance, it helps in reducing the speed of vehicles that tend to ignore the speed limit, ensuring the safety of students and others crossing the road, and directly impacts the reduction of traffic accidents. These reasons highlight the importance of adhering to traffic signals, thus supporting the fact that only authorized personnel, such as police officers, should have the power to override them when necessary.