The correct option is B Cocoon → Cotton
Cotton is a plant fibre obtained from the fruit of cotton plants.
Wool and silk are animal fibres. Wool is produced from the fleece of animals like sheep, goat, camel and yak, while silk is produced from the cocoons of silkworms.
Coir is a plant fibre obtained from the husk of the coconut. Nylon is a synthetic fibre made artificially from chemicals.