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
The most commonest cause of acute cor pulmonale is 
Select and explain. 
A. Pneumonia, B. Pulmonary thromboembolism, C. COPD, D. primary spontaneous pneumothorax
B: Pulmonary thromboembolism
Answer: B: Pulmonary thromboembolism 
Explanation: Ref Harrison 19 th ed pg 1454 ,1505 The most commonest cause of acute cor pulmonale is pulmonary thromboembolism. The most common cause of chronic cor pulmonale is COPD.