This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: VBDs, Arboviral & Viral Infections, Surface Infections, Subject name: Social & Preventive Medicine
[{'content': "'rK 39 antigen' is useful for diagnosis of: \nSelect and explain. \nA. Diphtheria, B. Diphtheria Tuberculosis, C. Lprosy, D. Kala azar", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Antigens used in different tests: Test (disease) Antigen used Mantoux test PPD Lepromin test Dhamendra antigen Schick test Schick toxin Dipstick test- malaria Histidine rich protein type II Kala azar Rk 39 antigen', 'role': 'assistant'}]