Explain the term “axle” in a vehicle:

A line along the vehicle, from bumper to bumper, which runs parallel to the vehicle's longitudinal axis.

The back beam of the chassis, to which the towing pin of the truck tractor is connected.

Shaft or system of drive shafts running the width of the vehicle, on which the wheels are installed.

The drive shaft that transmits the rotary motion from the gearbox to the differential.