This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Introduction and gametogenesis., Subject name: Anatomy
[{'content': 'Conceptus reaches uterine cavity at which stage? \nSelect and explain. \nA. 1 cell, B. 2 cell, C. 16 cell, D. 32 cell', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Conceptus enters uterine cavity on the 4th day in Advanced morula (>32) cell stage. Note: In IVF Transvaginal inseion into uterus is done at 8 cell stage.', 'role': 'assistant'}]