This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic histology, Subject name: Anatomy
Pneumocytes are present in ? 
Select and explain. 
A. Trachea, B. Bronchus, C. Bronchioles, D. Alveolus
D: Alveolus
Answer: D: Alveolus 
Explanation: Type 1 Pneumocyte helps in gaseous exchange. Type 2 Pneumocytes helps in production of surfactant.