The science teacher gave each group in the science lab a pair of wires for an investigation on electrical current.Susan noticed that the wires were made of metal,but they were covered with plastic.The wires were covered in plastic because
A.plastic is a good conductor and allows electricity to flow through it easily
B.plastic is a good insulator and does not allow electritiy to flow through it easily
C.plastic prevents the metal wire from melting
D.plastic is less expensive than metal
B?