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
Viral infection that is least transmitted transplacentally: 
Select and explain. 
A. Hepatitis B, B. Rubella, C. Herpes simplex, D. HIV
A: Hepatitis B
Answer: A: Hepatitis B 
Explanation: 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.