The correct answer is (b) Silk.
Copper, aluminium, and human body are all conductors of electricity. Silk is an insulator of electricity.
A conductor is a material that allows electricity to flow through it easily. Copper, aluminium, and human body are all conductors of electricity. Copper is a very good conductor of electricity, which is why it is used in electrical wiring. Aluminium is also a good conductor of electricity, and it is often used in electrical wiring instead of copper because it is less expensive. Human body is a conductor of electricity because it contains water, which is a good conductor of electricity.
An insulator is a material that does not allow electricity to flow through it easily. Silk is an insulator of electricity. Silk is made from a protein called fibroin, which is a long, thin molecule that is arranged in a way that does not allow electricity to flow through it.
I hope this helps!