- Metal is an electrical / electrical energy conductor
- Copper is a kind of metal
- Therefore, copper is an electrical conductor

- Copper is a kind of metal
- Metal is a kind of material
- Therefore, copper is a kind of material

- Copper is an electrical conductor
- Copper is a kind of material
- Hence, copper is the material that is an electrical conductor

Therefore, copper is the material that is an electrical conductor
[Question]Which of these substances conducts electricity the best?
[Context]- Metal is an electrical / electrical energy conductor 
- Copper is a kind of metal 
- Metal is a kind of material