- Metals usually have higher conductivity than nonmetals
- Metal is an electrical conductor
- So, metal is the material that has a higher conductivity than other materials

- Iron is a kind of metal
- Iron nails are made of iron
- So, iron nails are made of metal

- Metal is the material that has a higher conductivity than other materials
- Iron nails are made of metal
- So, an iron nail has a higher conductivity than other materials

Therefore, an iron nail has a higher conductivity than other materials
Which object is the best conductor of electricity?
- Iron is a kind of metal 
- Metals usually have higher conductivity than nonmetals 
- Metal is an electrical conductor 
- Iron nails are made of iron