Final answer:
The correct answer is c. Fuse link. A fuse link acts as a protective device in electrical circuits, breaking the connection if the current is too high, thus protecting the utility system from customer system problems.
Step-by-step explanation:
When used for service entrance protection and coordination, electric fuses provide a buffer to prevent in-plant problems from affecting service on the utility company system. The correct answer to the question is c. Fuse link. A fuse link has a metal strip with a low melting point that, when overheated by an excessive current, permanently breaks the connection of a circuit to a voltage source. Conversely, circuit breakers are automatic but restorable switches that act like fuses but can be reset, while interrupter switches and isolator switches serve different purposes in an electrical system. An isolation transformer for example, insulates the device being powered from the original source to prevent shock hazards.