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: Pharmacology
[{'content': 'All of the following have receptors which are transcription factors except \nSelect and explain. \nA. Insulin, B. Estrogen, C. Vitamin D, D. Glucocorticoid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]