This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic Bacteriology (Haemophilus, Yersinia, Spirochaetes, Ricketssia, Chlamydia, Mycoplasma and Miscellaneous Bacteria), Subject name: Microbiology
[{'content': 'An inhibitor was designed to block a biologic function in H. influenzae. If the goal of the experiment were to reduce the virulence of H. influenzae, the most likely target would be \nSelect and explain. \nA. Exotoxin liberator, B. Endotoxin assembly, C. Flagella synthesis, D. Capsule formation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The major determinant of virulence in H. influenzae is the presence of a capsule. There is no demonstrable exotoxin and the role of endotoxin is unclear. While one would expect that IgA protease would inhibit local immunity, the role of this enzyme in pathogenesis is yet unclear.', 'role': 'assistant'}]