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
[{'content': 'A foreign body completely obstructing the right main bronchus causes - \nSelect and explain. \nA. Decreased ventilation perfusion ratio, B. Increased ventilation in left lung, C. Perfusion doubles in right lung, D. Increased VF ratio in right lung', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]