This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
[{'content': 'Using histological criteria to date endometrial development, which of the following is the earliest sign of ovulation? not related - gyn \nSelect and explain. \nA. Gland coiling, B. Stromal edema, C. Neovascularization, D. Glycogen accumulation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: .', 'role': 'assistant'}]