ANS:C - 4.3

Cast iron is a ferrous alloy with a carbon content higher than that typically found in steel. The maximum carbon content in cast iron is approximately 4.3 percent. When the carbon content exceeds 2.11%, the material becomes a cast iron rather than a steel. The higher carbon content in cast iron contributes to its unique properties such as increased hardness, brittleness, and excellent castability. Cast iron is commonly used in applications where these properties are advantageous, such as in the manufacturing of engine blocks, pipes, and machinery components.