What does a blue and white sign typically indicate on highways?

Answer: B — Commercial services available

A blue and white sign on highways typically indicates the availability of commercial services. This can include services such as gas stations, restaurants, and lodging facilities that are available for travelers. These signs help drivers identify where they can find essential services while on the road, making travel more convenient and efficient. The other types of signs mentioned generally have different color schemes and functions. For instance, direction signs usually feature a different combination of colors, often green for guidance to destinations. Public park location signs might be more nature-themed in color, and speed limit signs are typically white with black text, focusing on regulations rather than services. Thus, recognizing blue and white signs specifically as indicators of commercial services is key for safe and informed travel.