This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gall Bladder & Bile Ducts, Subject name: Surgery
A female post open cholecystectomy through general Anesthesia after 12 hours she is dyspneic. Right lower lobe crepitations present. Probable cause is 
Select and explain. 
A. Drug collapse, B. Atelectasis, C. Pulmonary edema, D. Myocardial infarction
B: Atelectasis
Answer: B: Atelectasis 
Explanation: Ans. (b) AtelectasisRef: Bailey and Love 26th edition Page 273Post op complications - Respiratory:* MC post operative complications are - Hypoxemia, Hypercarbia and Aspiration in recovery room* Hypoxia reasons:# Upper airway obstruction due to secretion# Laryngeal edema# Recurrent laryngeal nerve injury after thyroid surgery# Hypoventilation related to anesthesia# Atelectasis# Pneumonia# Pulmonary edema of cardiac origin# Pulmonary embolism