This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
In ARDS which is damaged? 
Select and explain. 
A. Type 1 pneumocytes, B. Type 2 pneumocytes, C. Clara cells, D. Clara cells
A: Type 1 pneumocytes
Answer: A: Type 1 pneumocytes 
Explanation: In ARDS,alveolar capillary endothelial cells & type 1 pneumocytes(alveolar epithelial cells) are damaged/injured,leading to the loss of the normally tight alveolar barrier to fluid and macromolecules.As a result,edema fluid rich in protein accumulates in the interstitial & alveolar spaces.Condensed plasma proteins aggregate in the air spaces with cellular debris and dysfunctional pulmonary surfactant to form hyaline membrane whorls. Reference:Harrison's Medicine-20th edition,page no:2032