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': 'Long acting insulin preparations are frequently administered by: \nSelect and explain. \nA. Oral route, B. Intramuscular route, C. Intradermal route, D. Subcutaneous route', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]