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': 'Innate immunity is stimulated by which pa of bacteria that acts as a danger signal? \nSelect and explain. \nA. Cell wall carbohydrate sequence, B. Flagella, C. Bacterial cell membrane, D. Nucleus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Conserved antigenic patterns in bacteria such as unmethylated CpG DNA, flagellin, and lipid and carbohydrate structures in the bacterial cell wall serve as danger signals to activate innate immunity, resulting in local inflammation and theinflux of the macrophages, neutrophils, and dendritic cells.', 'role': 'assistant'}]