question: what makes metal orange?
choices.text: pigmentation heating tubular organ antigens chondrocytes radiation oxidation several genes
choices.label: A B C D E F G H
fact2: Metal turns to rust via oxidation.
combinedfact: oxidation makes metal orange
formatted_question: what makes metal orange? (A) pigmentation (B) heating (C) tubular organ (D) antigens (E) chondrocytes (F) radiation (G) oxidation (H) several genes