Which of the following is the best conductor of heat? 

Silver 

The correct answer is option 2. Silver.

Among the options provided, silver is the best conductor of heat. Silver (Ag) is renowned for its high thermal conductivity, making it one of the best conductors of heat among all metals. It has a thermal conductivity of approximately 429 W/(m·K) at room temperature, which is significantly higher than most other metals. This property makes silver highly valuable in various applications where efficient heat transfer is crucial, such as in electrical contacts, thermal interface materials, and high-performance heat sinks. So, the correct answer is Silver.