Definition: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Asthma is a disease in which the air passages of the lungs periodically become too narrow, often with excessive mucus production. This causes difficulty breathing, coughing, and chest tightness. An asthma attack may be triggered by allergens, strenuous exercise, stress, or other factors. Answer: lungs
Output:
What organ does asthma periodically cause to narrow?