The Knoop Hardness Number (KHN) of tooth enamel is most similar to which of the following materials?

Explanation

The Knoop Hardness Number (KHN) measures the hardness of materials. Enamel's hardness is closest to that of porcelain, making option C the correct choice. Pure gold, amalgam, and composite resins have different hardness values that do not match enamel as closely.