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
Most common cause of empyema is 
Select and explain. 
A. Bronchopleural fistula, B. Tubercular pneumonia, C. Bacterial pneumonia, D. Pleurisy
C: Bacterial pneumonia
Answer: C: Bacterial pneumonia 
Explanation: Empyema thoracic is collection of pus in pleural space and is synonymous with grossly purulent exudative parapneumonic effusions. Ref Harrison 19th edition pg 951