Switches commonly used for electric bells
A. Lever type
B. Push button type
C. Clutch type
D. All of the above

Hint: Electric bell is not an automatic bell. It is to be pressed by a person in order to ring. So as long as the button is not pressed the circuit will be open that means current won't flow through the circuit and as soon as the button is pressed the circuit will be closed and electricity passes through the circuit and the bell will ring.

Complete answer:
Before we discuss electrical bells we will learn what are the types of switches.
Lever switches contain actuators and cams and the center of the lever is situated on a rotating shaft. When any mechanical moving part comes in contact with the rotary axis of the lever, this in turn rotates the lever which is in contact with cam opens and closes the circuit. When the circuit is open, current won't flow and when the circuit is closed current will flow and the switch will be turned on.
Clutch type switches work just like bike clutches. When the transmission shaft is in contact with the gear box, the vehicle will move. The clutch is the mediator which maintains the contact between the transmission shaft and gearbox.
When we release the clutch the contact will be broken and the vehicle won't move as power is not transmitted to the gears from the transmission shaft.
This can be compared with electrical circuits too. Releasing and closing of clutch is like opening and closing of the electrical circuits.
Now when we talk about push button type switches, they are present in every home. When the switch is pressed the circuit will get closed and the bell will ring as current passes.

Therefore, Switches commonly used for electric bells Clutch type. So, the correct option is “Option (C)”.

Note: All these are mechanical switches i.e one intentionally operates them to close or open the circuits. There are automatic switches like fire alarms. They have bimetallic strips with different expansion coefficients. When there is fire, they expand at different rates and the circuit will get closed and alarm buzzes.