This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Ture about terminal bronchioles are all except ? 
Select and explain. 
A. Absence of cailage, B. Presence of clara cells, C. Absence of smooth muscles, D. Absence of submucous glands
C: Absence of smooth muscles
Answer: C: Absence of smooth muscles 
Explanation: Terminal bronchioles contain Clara cells which secrete a protein that lines the small air passages. Alveoli (alveolar sac) are lined by type 1 pneumocytes (95%) and type 2 pneumocytes (5%). Type 2 pneumocytes secrete surfactant and also helps in repair of alveoli after destruction of type- 1 pneumocytes. Pores of Kohn are present in alveolar wall to allow passage of bacteria and exudate between adjacent alveoli.Terminal bronchi contain maximum smooth muscle cells relative to wall thickness.Cailage is found in larynx, trachea and bronchi but not in bronchioles.Submucosal glands are paicularly numerous in medium-sized bronchi and disapperar in distal terminal bronchioles.