The correct option is B Cocoon → Cotton
Cotton is a plant fibres obtained from seeds 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.
Leather is produced from the skin of animals like cow, snake and buffalo.
Nylon is a synthetic fibre made artificially from chemicals.