Which one of these, is the most ductile metal?

Ductility is the physical property of a material associated with the ability to be hammered thin or stretched into a wire without breaking. The tensile material can be drawn into the wire.

Most metals, for example, gold (Au), silver (Ag), copper (Cu), and aluminium (Al), are ductile except a few like Zinc, arsenic, antimony, and mercury. 

Now, all the given options are ductile metals but Gold (Au) is the most ductile metal of all because it can be easily drawn into wires. It is also one of the most malleable metals also.

But still, the reason why most of the electrical wirings have copper wires than gold is that gold is an expensive metal and thus is used in making only jewellery.

Hence, the correct option is (B).