Concept:Silk is a natural fibre obtained from animals, and its primary chemical component is protein.Explanation:Silk fibre is produced from the cocoon of the silkworm. The main substance in silk is fibroin, which is a type of protein. Wool and silk are both animal fibres and are made of protein, not carbohydrate, fat, or minerals. Therefore, silk fibre is primarily composed of protein.Answer:C. Protein