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: Skin
[{'content': 'A patient has syphilis since 2 year. CSF examination was done & treatment staed. Which of the following test is most useful in monitoring treatment \nSelect and explain. \nA. TPI, B. VDRL, C. FTA, D. Dark ground microscopy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. VDRL', 'role': 'assistant'}]