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: Medicine
[{'content': 'Bronchial asthma is associated with raised levels of \nSelect and explain. \nA. Leukotrienes, B. PGI2, C. PGE2, D. Thromboxane', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Acute asthma attacks are often triggered by allergens or exercise. Inflammatory molecules called leukotrienes are one of several substances which are released by mast cells during an asthma attack, and it is leukotrienes which are primarily responsible for the bronchoconstriction Ref Davidson edition23rd pg 575', 'role': 'assistant'}]