Which of the given allotrope of carbon is a good conductor of electricity? 

Graphite 

The correct answer is option 3. Graphite.

Among the given allotropes of carbon, Graphite is a good conductor of electricity. Graphite is composed of carbon atoms arranged in layers of hexagonal rings. Each carbon atom in graphite is bonded to three other carbon atoms, forming strong covalent bonds within the layers. However, the layers themselves are held together by weaker van der Waals forces, allowing them to slide over each other easily. This unique structure gives graphite its lubricating properties and allows for the flow of electrons along the layers, making it a good conductor of electricity. Therefore, the correct answer is: Graphite.