A stop pushbutton is basically just a

• A. Normally open pushbutton
• B. Toggle switch
• C. Normally closed pushbutton switch
• D. Momentary pushbutton

Answer: (C)

Stop pushbuttons are designed to interrupt the control circuit when you need to stop the machine, and their defining characteristic is that they are normally closed. In the resting state the contacts are closed, allowing current to flow and the machine to run. When you press the button, the contacts open, breaking the circuit and stopping motion. Releasing the button lets it return to its closed state, ready to stop again if pressed. This normally closed arrangement is also a safety feature: a fault that opens the circuit will cause a stop, which is safer than a device that might fail in the run position. The other options don’t capture this default closed condition: a normally open pushbutton would only close when pressed (not suitable for stop), a toggle switch is a latching type, and a generic momentary pushbutton doesn’t specify the contact state at rest.