Insects, and some other invertebrates, exchange oxygen and carbon dioxide between their tissues and the air by a system of air-filled tubes called tracheae. Tracheae open to the outside through small holes called spiracles.
The stem supports the plant and because of the stem the plant is able to grow taller if needed
I wanna day C because let’s say you feed the mouse a piece a cheese and it gets a little be shiny but then when you feed it prices of hay it gets really shiny
1 for sure that’s what I say