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': 'Aboions in the second trimester is mostly due to: \nSelect and explain. \nA. Incompetent cervix, B. Defective genes, C. Tuberculosis, D. Trauma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Incompetent cervix', 'role': 'assistant'}]