Final answer:
Gold (Au) is the element among the given options that is malleable, ductile, and an excellent conductor of electricity, which are properties characteristic of metals.
Step-by-step explanation:
The element that is malleable, ductile, and a good conductor of electricity is gold (Au). Metals are known for being shiny, silvery, solid at room temperature (except mercury), and having the ability to be shaped or deformed without breaking, which is known as malleability. They can also be drawn into wires due to their ductility, and they typically conduct heat and electricity well. Among the options provided (S, B, Au, C), sulfur (S) is a nonmetal, boron (B) is a metalloid, carbon (C) can exist in various forms such as graphite or diamond (neither of which is a metal), and gold (Au) is a metal with all the characteristics in question: it is shiny, malleable, ductile, and an excellent conductor of electricity.