Final answer:
The correct option for a ground ring is #6 AWG. The American Wire Gauge (AWG) system is used to standardize the size of wires.
Step-by-step explanation:
The correct option for a ground ring is 2. A bare copper wire no smaller than #6 AWG. The American Wire Gauge (AWG) system is used to standardize the size of wires. In this system, a smaller gauge number corresponds to a larger wire diameter. Therefore, a #6 AWG wire would have a larger diameter than a #8 or #4 AWG wire.