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: Pathology
[{'content': "Reid's index is - \nSelect and explain. \nA. Increase in chronic bronchitis, B. Decrease in chronic bronchitis, C. Increase in bronchial asthma, D. Decrease in bronchial asthma", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]