CDCS-001 Exam Dumps : Certified Data Centre Specialist (CDCS)

Magnetic circuit breakers use an electromagnetic coil to pull a switch when a circuit carries too much current, thus tripping the circuit and preventing it from exceeding its rated amperage. 

AC can be transformed from a low voltage to a high voltage and back again with a transformer, while DC cannot. This makes it easier to distribute AC electricity over long distances and is why it is used more widely than DC electricity. A and B are also true, as wires carrying AC can be bare and don't need to be totally insulated. Wires have less resistance when carrying AC electricity, which is why it is more efficient than DC.