This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics, Subject name: Medicine
[{'content': 'Edward syndrome is: \nSelect and explain. \nA. Trisomy 21, B. Trisomy 18, C. Trisomy 13, D. 5p deletion', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: b', 'role': 'assistant'}]