Why do we use a plug key in the circuit?

we use a plug key in the circuit because to avoid from the electric shock ...

answer; i believe the correct answer is (4.0);

muslims control the north africa during the period of 1500 up

to 1800. they made a barrier to prevent further european exploration from

entering the africa from the north. however, the dutch ware still able to move

toward the interior with having south africa as one of the routes leading to

the east for trading with asia.