Alloys are consistent combinations made by mixing one metal with another metal or a nonmetal. Which of the following alloys on offer has a non-metallic component among its constituent parts?

The correct answer is steel.

Iron and carbon are combined to form the alloy metal known as steel wherein carbon is the non-metal.

Brass is an alloy of copper and zinc, hence not a correct answer. Oxygen is not an alloy and amalgam is not even an element, hence both are incorrect.