What natural fiber forms the coat of a sheep?

The coat of a sheep is primarily made of wool, which is a natural fiber derived from their fleece. Wool is composed of protein fibers that provide excellent insulation, moisture-wicking properties, and durability, making it ideal for clothing production. This fiber has been used for thousands of years in textiles, prized for its ability to retain heat while allowing breathability, which is why it is commonly used in various garments such as sweaters, suits, and outerwear. The other options—cotton, silk, and fur—do not originate from sheep. Cotton is a plant-based fiber, silk comes from silkworms, and fur refers to the pelts of animals, making wool the distinctive correct answer regarding the natural fiber sourced from sheep.