Erect _____________ sign 250' in advance of any section of roadway where traffic must travel on a planned surface.

The correct answer is to erect a grooved pavement sign 250 feet in advance of any section of roadway where traffic must travel on a planned surface because grooved pavement indicates that the surface has intentional grooves or patterns designed to enhance vehicle control, particularly in wet conditions. This advance warning is crucial for alerting drivers about the upcoming changes in road texture, which can affect traction and stability.

When drivers see this sign, they are made aware of the specific surface characteristics that may require them to adjust their speed or driving behavior. By providing this information well in advance, it encourages safer driving practices and helps reduce the likelihood of accidents caused by unexpected surface conditions.

The other options, while relevant to surface characteristics, do not serve as recognized warnings in the same way. A paved surface sign does not indicate a change that specifically requires driver caution, and as for coated and rough surfaces, they may not necessarily highlight the critical need for advance warning as effectively as grooved pavement, particularly in the context of maintaining traffic safety.