Final answer:
The grounding electrode must have at least 2 square feet of surface area exposed to the surrounding earth in order to effectively dissipate electrical energy.
Step-by-step explanation:
The correct answer is (c) Grounding electrode. A grounding electrode is used to connect an electrical system to the earth in order to protect against electrical faults and lightning strikes. It must have at least 2 square feet of surface area exposed to the surrounding earth in order to effectively dissipate electrical energy into the ground. An example of a grounding electrode is a grounding rod, which typically has a large surface area buried in the ground.