What does "controlled access" mean on a freeway?

Answer: C — You must use ramps to enter and exit

Controlled access on a freeway indicates that vehicles can only enter and exit the freeway at designated points, known as ramps. This design helps to manage the flow of traffic and enhances safety by minimizing interference from local road traffic. Ramps are strategically placed to allow for a smoother transition onto and off of the freeway, maintaining higher speeds and reducing congestion. The other choices do not accurately reflect the concept of controlled access; for instance, maximum speed is unrelated to access methods, and free entry and exit at any point would contradict the very nature of controlled access, which is to limit access points to maintain traffic flow. Additionally, while other vehicles are allowed on controlled access freeways, the main focus is on how access is managed.