Explanation:

- Silver

- Silver has the highest thermal conductivity of any element.

- It also holds the title for the highest light reflectance among all metals.

- This makes it valuable in applications needing efficient heat dissipation and reflective surfaces.

- Correct Answer

- Aluminium

- Aluminium has a decent thermal conductivity but not as high as Silver.

- It's widely used due to its lightweight and good conductivity.

- Copper

- Copper has excellent thermal conductivity, next only to silver among pure metals.

- Commonly used in wiring and heat sinks.

- Brass

- Brass is an alloy, not a pure element.

- Its thermal conductivity is lower than that of pure metals like copper and silver.