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': 'Best endometrial reaction In ectopic pregnancy is : \nSelect and explain. \nA. Arias stella reaction, B. Secretory phase, C. Decidual reaction without chorionic villi, D. Decidual reaction with chorionic villi', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Decidual reaction without chorionic villi', 'role': 'assistant'}]