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: Gynaecology & Obstetrics
[{'content': "Commonest chromosomal anomaly leading to spontaneous aboions is : \nSelect and explain. \nA. Trisomy 16, B. Trisomy 21, C. Tetraploidy, D. Turner's syndrome", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Trisomy 16', 'role': 'assistant'}]