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: Unknown
[{'content': 'Which of the following is the most common cause of 1st-trimester abortions : \nSelect and explain. \nA. Chromosomal deletions, B. Aneuploidy, C. Chromosomal translocation, D. Tetraploidy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans- B Aneuploidy Overall most common cause- Aneuploidy Most common cause among Aneuploidy types- Trisomy If both Trisomy and Aneuploidy are mentioned - Aneuploidy is the best answer since Trisomy is a type of Aneuploidy.', 'role': 'assistant'}]