This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of lipid, Subject name: Biochemistry
[{'content': 'True about bile acids is \nSelect and explain. \nA. 7 a hydroxylase is the rate limiting enzyme in the synthesis, B. They are derived from cholesterol, C. Cholic acid is primary bile acid, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref: M.N. Chatterjea - Textbook of Biochemistry, 8th edition, page no: 438,439', 'role': 'assistant'}]