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': 'Schick test is for - \nSelect and explain. \nA. Susceptibility to diphteria, B. Susceptibility to tetanus, C. Susceptibility to scarlet fever, D. Susceptibility to RF', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]