Which of the following best describes the purpose of the ground wire?
a. It is needed because the circuit of electricity to your home runs through the ground.
b. It is connected to the ground to increase the efficiency of the electric circuits in your home by using Earth's magnetic field.
c. It is connected to the ground as a safety precaution to prevent any stray current from reaching you when you touch a circuit.
d. It is only called "ground" by convention, but is normally used to create circuits that have a potential difference of 60 V.