What type of fibers do wool and silk belong to?

Wool and silk are categorized as natural fibers because they are obtained directly from animal sources. Wool comes from the fleece of sheep and is a protein fiber, while silk is produced by silkworms and is known for its luster and softness. Natural fibers like these are biodegradable and typically have favorable characteristics such as breathability, moisture-wicking properties, and comfort against the skin.

In contrast, synthetic fibers are man-made and include materials like polyester and nylon, which are derived from petrochemicals. Manufactured fibers, while sometimes also plant-based or animal-based, typically undergo extensive chemical processing to create fibers such as rayon or acetate. Asbestos fibers, on the other hand, are not a common type of fiber used in fashion or textiles today and are primarily associated with insulation and fireproofing materials, posing health risks rather than being usable in clothing fashion.

Thus, the classification of both wool and silk as natural fibers highlights their origins and natural properties, making option A the correct choice.