What is the top speed limit for heavy trucks on the open highway in the daytime?

Answer: B — 60 mph

The top speed limit for heavy trucks on the open highway during the daytime is set at 60 miles per hour. This regulation is designed to promote safety on the roads, as heavier vehicles require more time and distance to stop compared to lighter vehicles. Limiting their speed helps reduce the risk of accidents and enhances overall traffic flow. While other choices suggest higher speeds, they do not adhere to the established safety regulations for heavy trucks, which emphasize the need to maintain control and stability at lower speeds due to their weight and size. Therefore, a limit of 60 mph strikes a balance between efficiency and safety for both heavy truck operators and other road users.