You will need to be familiar with the concepts Semi-conductor, Insulator, and Conductor before you can find the right answer.
Conductors allow electrons to be transferred quickly from one end of the conductor to the other. This allows it to transfer electricity. Conductors have no band gap between the conduction band or valency bands.
eg: Iron and human body, copper or aluminium, water, etc
Insulator electrons cannot be transferred from one end of the device to the other. It doesn’t allow electricity to pass through it. Insulators have a large gap between the conduction band (valency band) and the conduction band.
eg: Wood, Rubber, Pure Water etc…
Metals falls under the category Conductors. The electrons are loosely bound with the nucleus so there is no gap between the conduction band or valency bands. So electrons can easily flow through metals