Concept:Silk is obtained from the cocoon, which is the protective covering spun by the silkworm during its pupal stage.Explanation:The silkworm (larva) feeds on mulberry leaves and grows for about 30 days. It then spins a cocoon around itself using a single continuous silk thread. Inside the cocoon, the larva transforms into a pupa. The cocoon is collected at this pupal stage to extract the silk. The pupa later becomes an adult moth. Thus, silk is harvested from the stage when the organism is a pupa inside the cocoon.Answer:B. Pupa