Which of the following is classified as an authorized emergency vehicle?

An authorized emergency vehicle is defined by the Texas Transportation Code as a vehicle that is equipped with lights and sirens, specifically designed for responding to emergencies. A fire department vehicle fits this classification because it is built and designated for emergency response situations, including firefighting and rescue operations.

In contrast, a standard passenger car, a personal vehicle used for commuting, and a public transportation bus do not serve the same specialized purpose and lack the emergency equipment that qualifies them as authorized emergency vehicles. While public transportation buses may have their own designated protocols for emergencies, they are not classified under the same category as vehicles specifically designed for emergency responses like fire trucks or ambulances. Thus, identifying a fire department vehicle as an authorized emergency vehicle is consistent with the definitions outlined in relevant traffic laws and regulations.