This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'Viral infection that is least transmitted transplacentally: \nSelect and explain. \nA. Hepatitis B, B. Rubella, C. Herpes simplex, D. HIV', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Hepatitis B (Ref: Arora Microbiology, 3rd/e, p. 702)Rubella and HSV are teratogenic virus, so their transplacental transmission is expected to be high, HIV have 30% transplacental transmission but HBV is least transmitted transpalcentally.", 'role': 'assistant'}]