This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology Pa-2 (RNA Virus Pa-1,2 & Miscellaneous Viruses), Subject name: Microbiology
[{'content': 'All are features of dengue hemorrhagic fever expect: \nSelect and explain. \nA. Thrombocytopenia, B. Narrow pulse pressure, C. Hematocrit elevated, D. Positive torniquet test.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 1. Criteria for diagnosis of dengue hemorrhagic fever (DHF): o Fever - acute, high, continuous for 2-7 days. o Positive tourniquet test o Enlargement of liver o Laboratory evidence o Thrombocytopenia (< 1000,000/mm3) o Haemoconcentration (Haematocrit raised by >20%) Narrow pulse pressure is not seen in DHF', 'role': 'assistant'}]