This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': 'Which of the following exposure carries the maximum risk of transmisstion of HIV - \nSelect and explain. \nA. Sexual intercourse, B. Blood transfusion, C. Trans-placental, D. Needle prick', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]