In the respiratory system certain structures allow air to pass from the trachea to the lungs. They are lined with thin muscles and coated with epithelial cells. These structures are called A. bronchial tubes.
B. alveoli.
C. bronchioles.
D. lobules.

steady state because it the only on that maes sense

one time i was looking at my neighbors screen door to see if the door was open i was squinting like a fool for 10 minutes before realizing he was starring back i then died from embarrassment and am now typing this from the ghost world