Which of the following is classified as a natural fiber?

Cotton is classified as a natural fiber because it is derived from the cotton plant. Natural fibers are made from plant, animal, or mineral sources, and they retain their natural state and structure through the manufacturing process. In the case of cotton, the fibers are harvested from the seed bolls of the cotton plant, cleaned, and then spun into yarn or thread for fabric production.

This characteristic distinguishes it from other options listed. For example, silk is also a natural fiber derived from silkworms, but it is not the correct answer in this context as the focus may be on commonly used fibers like cotton. Acetate and polyester, on the other hand, are synthetic fibers made from chemical processes. Acetate is made from cellulose acetate, while polyester is a petroleum-based product, meaning neither of these fibers originates from a natural source, which reinforces why cotton is the best representative of natural fibers in this question.