Which of the following are the ingredients of gun metal?

Option B

Gunmetal, also known as red brass in the United States, is a type of bronze – an alloy of copper, tin, and zinc. Proportions vary by source, but 88% copper, 8–10% tin, and 2–4% zinc is an approximation. Originally used chiefly for making guns, it was eventually superseded in this department by steel.