Mr. Garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is __________.

• A. gold
• B. aluminum
• C. iron
• D. copper

Answer: (C)

The correct answer is linked to the composition of steel, which is primarily made of iron. Steel is an alloy primarily consisting of iron, often combined with carbon and other elements to enhance its properties. When Mr. Garcia uses magnets to hold a poster on a steel filing cabinet, the magnetic properties of iron are the key factor. Iron is ferromagnetic, meaning it can be magnetized and is attracted to magnets.

Other metals listed, like gold, aluminum, and copper, do not possess the same magnetic properties. Gold and copper are non-ferromagnetic and do not react to magnets, while aluminum is generally non-magnetic under normal conditions. This fundamental characteristic of iron enables the effective use of magnets on steel surfaces, making it the appropriate choice for this context.