What is the primary characteristic of stainless steel?

The primary characteristic of stainless steel is its composition, which includes chromium and often nickel. The presence of chromium is crucial as it forms a thin layer of oxide on the surface, which protects the metal from corrosion. This characteristic makes stainless steel highly resistant to rust and staining, which is essential in many applications, particularly in environments exposed to moisture and chemicals. The additional inclusion of nickel enhances the toughness and ductility of the steel, contributing to its overall strength and longevity.

Other options depict characteristics that do not accurately represent stainless steel. For instance, malleability and softness are not defining traits of stainless steel; it is known for its strength and durability. Similarly, low resistance to corrosion contradicts the very nature of stainless steel, as its corrosion-resistant properties are what make it desirable in various applications. Lastly, stating that stainless steel is only used in construction materials is misleading, as it is utilized in many areas, including kitchenware, appliances, medical instruments, and automotive applications, among others.