Correct Option: C

The saliva from the salivary gland of silkworm is the component of silk and is produced by the larva of the silkworm (cocoon). The Chinese silkworm (B. mori) has been used in commercial silk production for centuries. The adult, which has a wingspan of about 2 in. (50 mm) and a thick, hairy body, lives only two or three days. The female lays 300–500 eggs. The pale, naked larvae fed on mulberry leaves until pupation begins, when they are about 3 in. (75 mm) long. They spin a cocoon of one continuous white or yellow silken thread, about 1,000 yards (900 m) long. The pupa is killed with hot air or steam to preserve the thread intact.