Which type of cable tray is best described as a ventilated bottom with side rails?

A ventilated channel is a smaller, U-shaped raceway without distinct separate side rails, typically used for lighter cable loads in shorter runs.

A ladder tray uses horizontal rungs spanning two side rails with no continuous bottom panel, resembling a ladder rather than a trough.

A spline tray uses a central spine with protruding wire elements to separate cables, not a ventilated bottom with side rails.

A ventilated trough cable tray is defined by its ventilated (perforated or louvered) bottom surface with raised side rails, which exactly matches the question description. This design allows airflow and drainage through the bottom while providing structural support via the rails, distinguishing it from all other tray types.

A basket tray is constructed from welded wire mesh forming an open basket shape, not a ventilated sheet-metal bottom with side rails.