This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET Jan 2020, Subject name: Physiology
In a preterm baby with Respiratory distress syndrome, which type of cell is deficiency? 
Select and explain. 
A. Type 1 alveolar cell, B. Type 2 alveolar cell, C. Alveolar capillary endothelial cells, D. Bronchial mucosal epithelial cell
B: Type 2 alveolar cell
Answer: B: Type 2 alveolar cell 
Explanation: Cells in Alveolar Epithelial Lining- Type I pneumocytes-Gas exchange occurs across them. .Cover93%surface area of alveoli. Type II pneumocytes -synthesizesurfactant. Direct / indirect injury to type 2 cells lead to ARDS.Cover 5%surface area of Alveoli. When there is alveolar injury, type I cells degenerate and are replaced by type II cells. Type II cells are thus responsible for regeneration of epithelium. Type I and type II pneumocytes exist in a ratio of 1:1. Type III pneumocytesact as chemoreceptors.Cover 2% surface area of Alveoli.