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: Pathology
[{'content': 'Edwards syndrome is due to:(1986) \nSelect and explain. \nA. Trisomy 21, B. Trisomy 18, C. 18 p, D. Trisomy 13', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans: b (Trisomy 18)Ref: Robbin's Patho, 7thed, p. 177 & 6thed, p. 172", 'role': 'assistant'}]