The thermal conductivity of silver and copper is high because they have following binding:

Silver and copper are metals. They form metallic bonds. They consist of moving electrons immersed in a sea of ​​well-charged metal cations. These moving electrons can move from one end of the metal to the other. So, they supply electricity.

Metallic bonding is a property of metals. Because they have a lot of delocalized electrons in tight binding types of metallic bonds, the strength of metallic bonds for various metals reaches a maximum near the center of the transition metal series. As a result of their membership in the transition metal series and the metallic characteristics they display, silver and copper have excellent thermal conductivity. The capacity of a substance to transfer heat from one location to another without causing the material as a whole to move is known as thermal conductivity. Since metals have a lot of free electrons, heat can also be transferred through their electrical conductivity. Due to their metallic connection, free electrons can travel around the material freely and transmit thermal energy. They can delocalize both the 3d and 4s electrons, particularly for transition metals. The strength of the attractions and the metallic bonding increase with the number of electrons involved. As a result, the cation's effective nuclear charge increases and its size decreases. As a result of their metallic connection, silver and copper are said to have a high thermal conductivity.

Hence, the correct option is A.