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: Medicine
[{'content': 'Which of the following correlates well with the "severe" type of bronchial asthma exacerbation: March 2011 \nSelect and explain. \nA. Bradycardia with HR less than 100/ min, B. Pulsus paradoxus less than 10/min, C. Tachypnea with RR less than 30/min, D. Usual use of accessory muscles of respiration', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. D: Usual use of accessory muscles of respiration Bronchial asthma: Hyper-responsiveness of airways with bronchoconstriction Increased leukotrienes Histology: Creola bodies, - Charcot Layden crystals, - Curschmann's spiral FEV1 is the parameter to improve maximum on bronchodilator therapy", 'role': 'assistant'}]