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: Microbiology
[{'content': 'Most potent chemoattracatant is: \nSelect and explain. \nA. Leukotriene B4, B. Leukotriene C4, C. Leukotriene D4, D. Leukotriene E4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a. Leukotriene B4', 'role': 'assistant'}]