What type of switch is not manually operated?

A switch that is not manually operated typically refers to a switch that operates automatically, based on some sort of condition or input rather than human action. In this context, the options provided mostly include switches that are designed for manual operation, which means they require a physical action to be activated or changed.

When looking at the choices given, a pushbutton, a selector switch, and a knife switch are all types of switches that require manual intervention to operate. A pushbutton switch requires someone to press it, a selector switch requires a manual choice between different settings, and a knife switch has to be moved physically to either the open or closed position.

Therefore, the correct answer, which indicates that none of the listed switches are automatically operated, reinforces the understanding that the presented options all involve a manual action. This highlights that there are indeed switches that are not operated manually, which would be a type of switch either activated by automatic means or controlled by external factors such as timers, sensors, or relays.