This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Chemoattractant is - \nSelect and explain. \nA. C5a, B. C1, C. C3, D. C2', 'role': 'user'}, {'content': 'Answer: A \nExplanation: - the transmigration of leucocytes after crossing several barriers to reach the interstitial tissue is a chemotactic factor mediated process called chemotaxis. - C5a and C3a are anaphylatoxins and powerful chemoattractant. Reference : Harsh mohan text book of pathology, 7 th edition,Pg no:120 <\\p>', 'role': 'assistant'}]