Which of the following is a power transmission device for a stacker?

A power transmission device for a stacker is primarily responsible for transmitting power from the engine or motor to the wheels and drive system, allowing the vehicle to move and maneuver effectively. The differential is the correct answer because it plays a crucial role in allowing the wheels to rotate at different speeds, especially when turning. This is essential for improving traction and stability when the stacker navigates corners or uneven surfaces.

The other options do not function as power transmission devices. The diversion steering wheel is primarily used for steering and control rather than transmitting power. The brake lever is a control mechanism that engages the braking system to slow down or stop the vehicle, which does not involve direct power transmission. The ignition device is responsible for starting the engine but does not transmit power during operation. Therefore, the differential is the key component that facilitates effective power transmission in a stacker.