This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pregnancy in Rh-negative Women, Subject name: Gynaecology & Obstetrics
[{'content': 'Causes of Hydrops fetalis: \nSelect and explain. \nA. Parvovirus, B. Herpes, C. CMV, D. HIV', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. (A) Parvovirus(Ref: William's Obstetrics 25th Ed; Page No 309)Parvovirus B19 is the most common infectious cause of hydrops fetalis.Parvovirus B19 infects fetal erythroid progenitor cells and cause anemia.Severe anemia leads to high-output cardiac failure and hydrops fetalis.", 'role': 'assistant'}]