Trailers receive air from where?

Trailers receive air from the tractor because the air brake system in a combination vehicle, such as a truck and trailer, is designed to ensure that both units operate cohesively. The tractor is equipped with a compressor that generates the air needed for the brake system, and this compressed air is then directed through lines to the trailer. This connection allows the trailer’s braking system to function properly and synchronize with the tractor's braking system, ensuring the vehicle can stop safely and efficiently.

The other options refer to components or systems that play a role in generating or storing air but are not where the trailer directly receives air from. The pump typically refers to the component located in the compressor that supplies air, while the compressor is responsible for generating the compressed air itself. The reservoir is a storage component where air can be kept for use in the braking system but is not the origin of the air for the trailer brakes. Thus, the most direct and accurate source of air for the trailer is indeed the tractor.