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
True about bile acids is 
Select and explain. 
A. 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
D: All of the above
Answer: D: All of the above 
Explanation: Ref: M.N. Chatterjea - Textbook of Biochemistry, 8th edition, page no: 438,439