The correct option is **C. Copper**. ### Detailed Explanation: 1. **Understanding Alloys**: - An alloy is a mixture of two or more elements, where at least one of the elements is a metal. Alloys are created to enhance certain properties such as strength, corrosion resistance, and malleability. 2. **Composition of Brass**: - Brass is primarily an alloy of copper and zinc. The typical composition of brass can vary, but it usually contains about 55% to 95% copper and the remainder is zinc. The addition of zinc to copper improves its strength and corrosion resistance. 3. **Composition of Bronze**: - Bronze is primarily an alloy of copper and tin. The typical composition of bronze can vary as well, but it usually contains about 60% to 90% copper and the remainder is tin. The addition of tin to copper enhances its hardness and resistance to corrosion. 4. **Common Constituent**: - Both brass and bronze contain copper as a major component. In brass, copper is the primary metal, while in bronze, copper is also the primary metal, albeit combined with tin instead of zinc. ### Why the Other Options are Incorrect: - **A. Tin**: - Tin is a significant component of bronze but is not found in brass. Therefore, it cannot be a common constituent of both alloys. - **B. Zinc**: - Zinc is a major component of brass but is not present in bronze. Thus, it cannot be a common constituent of both alloys. - **D. Lead**: - Lead is not a primary component of either brass or bronze. While lead can be added to some brass alloys to improve machinability, it is not a standard constituent of either alloy. Therefore, it cannot be considered common to both. ### Summary of Key Points: - **Brass** is primarily an alloy of **copper and zinc**. - **Bronze** is primarily an alloy of **copper and tin**. - The common constituent in both brass and bronze is **copper**. - Other options (tin, zinc, lead) are not common to both alloys. ### Revision Summary: - Brass = Copper + Zinc - Bronze = Copper + Tin - Common metal in both alloys = Copper - Tin, Zinc, and Lead are not common to both alloys.