This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Anatomy
[{'content': 'Decidual space is obliterated by: \nSelect and explain. \nA. 10 th week, B. 12 th week, C. 18 that week, D. 16 th week', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Decidual space is the space between decidua capsularis and parietalis seen in early pregnancy because the gestational sac does not fill the uterine cavity. By 14-16 weeks the gestational sacred has enlarged to fill the uterine cavity completely by 4 th month (16 weeks). Ref: Datta Observe 9e pg 22.', 'role': 'assistant'}]