Concept:Natural fibres are obtained from plants or animals. Synthetic fibres are man-made.Explanation:Jute comes from the bark of the jute plant. Silk comes from the cocoon of silkworms. Both are natural fibres.Rayon is made from wood pulp and is a synthetic fibre. Polyester is also a man-made synthetic fibre.Thus, the only pair containing two natural fibres is jute and silk.Answer:Option C: Jute and silk