This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Heimlich valve is used for drainage of- 
Select and explain. 
A. Pneumothorax, B. Hemothorax, C. Emphyema, D. Malignant pleural effusion
A: Pneumothorax
Answer: A: Pneumothorax 
Explanation: None