This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
Succinyl CoA is formed by 
Select and explain. 
A. Valine, B. Isoleucin, C. Methionine, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Valine,isoleucine and methionine are influx of TCA cycle intermediate propionyl CoA which is conveed to succinyl CoA.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 253, fig 19.9