This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': "Which of the following is agglutination test - \nSelect and explain. \nA. Widal test, B. VDRL, C. Ascoli's test, D. Kahn test", 'role': 'user'}, {'content': "Answer: A \nExplanation: Widal test is a tube agglutination test. Agglutination reaction is when a paiculate antigen is mixed with its antibody in the presence of electrolytes at a suitable temperature and pH, the paicles are clumped or agglutinated. two antigens, flagellar H antigen a, d somatic O antigen are used in Widal test. Reference : Anathanarayan & paniker's 9th edition, pg no:108,109 <\\p>", 'role': 'assistant'}]