In which of the following stages of silkworm, silk is secreted

The correct answer is A. Larva.

Silk is a natural protein fiber that is produced by silkworms. Silkworms are the larvae of the mulberry silk moth, Bombyx mori. The silkworm starts to secrete silk when it is about three days old. The silk is used to build a cocoon around itself. The cocoon is made up of one continuous thread of silk that can be up to 1,500 meters long. The silkworm pupates inside the cocoon and emerges as an adult moth about two weeks later.

The other options are incorrect because:

• Option B, Pupa: The pupa is the stage in the life cycle of a silkworm between the larva and the adult moth. During this stage, the silkworm does not eat or move. It is encased in a cocoon that it has made from silk.
• Option C, Egg: The egg is the first stage in the life cycle of a silkworm. The egg is laid by the adult moth. The egg hatches into a larva, which is the stage in the life cycle of a silkworm that eats and grows.
• Option D, Adult: The adult silk moth is the final stage in the life cycle of a silkworm. The adult moth does not eat. It mates and lays eggs.