Drivers operating vehicles on a divided highway must _________ unless directed otherwise by a sign, traffic control device, or police officer.

The correct answer is that drivers operating vehicles on a divided highway must drive to the right of the median. This is a fundamental traffic law that helps maintain order and safety on the road. Divided highways are designed with a physical barrier or median separating opposing lanes of traffic, and adhering to the right side of the median keeps vehicles in their appropriate lanes. This structure is essential in preventing head-on collisions and promoting smoother flow of traffic.

Driving to the right of the median ensures that each direction of traffic is properly segregated, reducing the chances of accidents caused by vehicles crossing into oncoming lanes. It is vital for drivers to follow this rule unless there are specific instructions from signs, traffic control devices, or police officers directing them otherwise.

In contrast, driving on the left side of the median or avoiding the right side could lead to confusion and increased hazards on the roadway. Furthermore, the option concerning speed limits does not address the fundamental guidelines for operating a vehicle on divided highways, and thus is not relevant in this context. Following the established driving rules is crucial for maintaining safety and adherence to the law.