Household 120-V Outlets Are Made to Accept Three-Pronged Plugs

Multiple Choice

Household 120-V outlets are made to accept three-pronged plugs.One of the prongs attaches to the "live" wire at 120 V,and another attaches to the "neutral" wire that is connected to ground.What is the round third prong for?

A) It serves as a backup to the hot wire.
B) It lets the appliance run if the neutral wire breaks.
C) It connects the case of the appliance directly to ground for safety purposes.
D) Nothing electrical,it is for mechanical sturdiness.