Which color is used for service signs that direct motorists to service facilities?

The correct choice, blue, is used for service signs that guide motorists to various service facilities such as gas stations, restaurants, and rest areas. This color standardization is important as it allows drivers to quickly and easily identify and navigate towards services they may need while traveling.

Service signs in blue are designed to provide essential information without conflicting with other road signs. Red typically indicates stop or prohibition, green is used for directional guidance, and yellow is commonly associated with warning signs; thus, using blue for service facilities ensures clarity and aids in better traffic flow and safety for motorists seeking assistance or amenities.