This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
[{'content': 'Which of the following is not a tube test? \nSelect and explain. \nA. VDRL, B. Kahn test, C. Widal test, D. Paul bunnel test', 'role': 'user'}, {'content': 'Answer: A \nExplanation: VDRL: Venerial disease Research Laboratory Test Ref: Ananthanarayana & panikers 9th edition', 'role': 'assistant'}]