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: Anatomy
[{'content': 'True about morula: \nSelect and explain. \nA. 8-cell stage, B. 16-cell stage, C. Solid mass with fluid inside, D. Ach. Barrier present', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B. i.e. 16 cell stage', 'role': 'assistant'}]