The main switch at the distribution board, used to switch on or off the mains is the
A. single pole switch
B. Double pole switch
C. Both
D. None

Hint: We know that electric switches are the devices of much significance that can be used to break or make an electric circuit manually as well as automatically. ON/OFF technique is the technique on which its working principle depends. Now you could read the question and find the answer.

Complete step-by-step solution:
In the question, we are asked to find the type of switch that is used to switch on or off the mains at the distribution board. Let us first recall what a switch is.
Any device that is used to interrupt the flow of electrons in a circuit could be called an electrical switch. These are crucial binary devices that are either completely ‘ON’ or completely ‘OFF’. There are actually lots of options available in the types of switches that are available in the market.
It is the double pole switch that is commonly used in industrial applications, especially the main switch at the distribution board. This category of switches can also be found in some of the home wiring systems. They are rated for about 30 amps which when compared to the other standard double switches with 15-20amps is pretty high.
Therefore, we found that the main switch at the distribution board, used to switch on or off the mains is the double pole switch. Hence option B is true.

Note: Some of the other configurations are the single pole switch and the toggle switch. Single pole switches basically are the general purpose switches that are used to control various lights or other devices all from a single location. Toggle switches are the ones that are pushed up and down mechanically and are used as light control switches.