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: Anatomy
All the following features are seen in ARDS except 
Select and explain. 
A. Pulmonary oedema, B. Reudced lung compliance, C. Hypercapnia, D. Stiff lung
C: Hypercapnia
Answer: C: Hypercapnia 
Explanation: ARDS, the presence of alveolar and interstitial fluid and the loss of surfactant can lead to a marked reduction of lung compliance. Without an increase in end-expiratory pressure, significant alveolar collapse can occur at end-expiration, with consequent impairment of oxygenation. In most clinical settings, positive end-expiratory pressure (PEEP) is empirically set to minimise Fio2(inspired O2 percentage) and maximize Pao2(aerial paial pressure of O2). On most modern mechanical ventilators, it is possible to construct a static pressure-volume curve for the respiratory system.The impact of hypercapnia in ARDS. The impact of hypercapnia has not been clearly elucidated and is still controversial given its disparate effects . Neveheless, it has come to be seen as a major factor in ARDS Ref Davidson edition23rd pg 199