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: Social & Preventive Medicine
[{'content': 'Tourniquet test is used in the diagnosis of: \nSelect and explain. \nA. Dengue, B. Scurvy, C. Malaria, D. Hypeension', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Tourniquet test is used in diagnosis of dengue haemorrhagic syndrome (DHS). The test is performed using a blood pressure cuff which is inflated to a point midway between the systolic and the diastolic blood pressure for 5 minutes. In DHS, test usually gives a positive result, i.e more than 20 petechiae per 2.5 square cm. Ref: Park 21st edition, page: 227.', 'role': 'assistant'}]