The correct answer is option 3 - spiracles. Cockroaches do not have lungs like mammals do. Instead, they have tiny openings called spiracles on the sides of their body. These spiracles allow air to enter into the cockroach`s respiratory system. The spiracles are connected to a network of tubes called tracheae, which deliver the oxygen directly to the cockroach`s cells. This system of respiration is different from gills, which are used by aquatic animals to extract oxygen from water. Similarly, cockroaches do not obtain oxygen through their skin, as their exoskeleton acts as a barrier. So, in conclusion, air enters the body of cockroaches through the spiracles.