What emblem identifies vehicles that travel at speeds of 25 mph or less?

The emblem that identifies vehicles traveling at speeds of 25 mph or less is a fluorescent orange triangle with reflective borders. This specific design is widely recognized and used to enhance visibility, ensuring that slower-moving vehicles, such as agricultural equipment, construction vehicles, and some non-traditional vehicles on public roads, can be easily seen by other motorists. The bright color and reflective borders help maximize the triangle's visibility during daylight and at night, promoting safety for both the slower vehicle operators and other drivers on the road.

In contrast, the other options represent different types of signage or emblems that do not pertain to the identification of slow-moving vehicles. For example, a black triangle typically signifies caution, while a yellow rectangle with red edges might indicate various warnings. A blue square is generally used for regulatory signs concerning parking or services. The fluorescent orange triangle is specifically designed and standardized for the purpose of indicating slow-moving vehicles, making it the correct choice in this context.