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
Which of the following is a secondary bile acid? 
Select and explain. 
A. Cholic acid, B. Chenodeoxy cholic acid, C. Litho Cholic acid, D. None
C: Litho Cholic acid
Answer: C: Litho Cholic acid 
Explanation: Bile acids are formed from cholesterol.Types(a) Primary bile acids: They are synthesised in the liver from cholesterol. They are mainly two:Cholic acid: Quantitatively the largest in amount in bile.Chenodeoxy cholic acid.(b) Secondary bile acids: They are produced in intestine from the primary bile acids by the action of intestinal bacteria, they are produced by deconjugation and 7-a-dehydroxylation. They are mainly two:Deoxycholic acid: Formed from cholic acid.Lithocholic acid: Formed from chenodeoxycholic acid.Ref: M.N. Chatterjea - Textbook of Biochemistry, 8th edition, page no: 438