Concept:Stainless steel is a corrosion-resistant alloy whose main components are iron and chromium.
Explanation:Iron alone is strong but rusts easily when exposed to moisture and air.
Adding chromium changes the properties of the metal significantly.
Chromium forms a thin, invisible layer of chromium oxide on the surface.
This protective layer stops oxygen and water from reaching the iron underneath.
Therefore, the alloy resists rusting and staining.
Other metals such as nickel and molybdenum may be added in small amounts to improve strength or heat resistance, but they are not essential for the basic definition.
Stainless steel is not made from iron and zinc, copper and tin, or only iron and carbon.
Its essential alloying element is chromium, alongside iron.
Answer:C. Iron and chromium