In a vehicle, what supports the window glass and prevents it from falling?

The choice that identifies the components which support the window glass and prevent it from falling is accurate because track channels and stop blocks work together to ensure the stability and movement of the window. Track channels guide the window as it moves up and down, keeping it aligned within the frame of the door. These channels hold the window securely in place, preventing it from dropping out of position.

The stop blocks play a crucial role as well; they serve as limits for the movement of the window glass, preventing it from sliding too far down or being forced out of the frame. This combination allows for the smooth operation of the window while ensuring safety and security when it is closed.

The other options focus on components that may have functions related to window operation but do not specifically address the joint task of both supporting the window glass and preventing it from falling as effectively as the track channels and stop blocks.