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': 'B19 usually causes a very mild disease. Two groups of people for whom it can be serious, however, are? \nSelect and explain. \nA. teenagers and pregnant women, B. pregnant women and sickle-cell anemics, C. the sexually promiscuous and drug addicts, D. alcoholics and asplenics', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Primary infection in pregnant women is very serious and can result in death of the fetus. In patients with sickle-cell disease, the virus can initiate a transient aplastic crisis. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition', 'role': 'assistant'}]