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
[{'content': 'Most common cause of empyema is \nSelect and explain. \nA. Bronchopleural fistula, B. Tubercular pneumonia, C. Bacterial pneumonia, D. Pleurisy', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Empyema thoracic is collection of pus in pleural space and is synonymous with grossly purulent exudative parapneumonic effusions. Ref Harrison 19th edition pg 951', 'role': 'assistant'}]