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: Biochemistry
For which of the following enzymes, thiamine pyrophosphate (TPP) acts as Cofactor 
Select and explain. 
A. Pyruvate Dehydrogenase, B. Alpha Ketoglutarate dehydrogenase, C. Branched chain ketoacid dehydrogenase, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None