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': 'Advantages of oral controlled release drug dilivery are all except? \nSelect and explain. \nA. Maintanence of optimum drug concentration, B. Increased duration of therapeutic effect, C. improved efficiency of treatment, D. Lower cost of production', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Lower cost of production", 'role': 'assistant'}]