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: Physiology
[{'content': 'The WBC that is considered “second line of defence” is: \nSelect and explain. \nA. Neutrophil, B. Eosinophil, C. Basophil, D. Monocyte', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Monocyte is considered as the second line of defence.\n\xa0\nPhagocytosis by Macrophages.\nMacrophages are the end-stage product of monocytes that enter the tissues from the blood. When activated by the immune system, they are much more powerful phagocytes than neutrophils, often capable of phagocytizing as many as 100 bacteria. They also have the ability to engulf much larger particles, even whole RBCs or, occasionally, malarial parasites, whereas neutrophils are not capable of phagocytizing particles much larger than bacteria. Also, after digesting particles, macrophages can extrude the residual products and often survive and function for many more months.\nReference: GUYTON AND HALL TEXTBOOK OF MEDICAL PHYSIOLOGY, THIRTEENTH EDITION(INTERNATIONAL EDITION ) page no 458', 'role': 'assistant'}]