Solution:Concept- The tracheae, also known as the silkworm's respiratory system, are a collection of stiff tubes. Through pairs of pores known as spiracles, the tracheas were connected to the environment.
1. The silkworm's respiratory system is called the trachea.
2. The lateral series of spiracles and the radiating branches of the bronchial are connected by long air tubes called tracheae.
3. The tracheae transport oxygen from the insect's spiracles to its body.
4. The oxygen is finally delivered to the organ tissues by the bronchial branches.
5. Tracheae assist insects exchange carbon dioxide and oxygen.
Hence, the correct answer is option 2- Tracheae