This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Link reaction, Subject name: Biochemistry
Thiamine deficiency results in decrease energy production, because TPP: 
Select and explain. 
A. Interferes with Alcohol metabolism, B. Interferes with Transketolase activity, C. Is cofactor for pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase, D. Interferes with Energy production from amino acids
C: Is cofactor for pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase
Answer: C: Is cofactor for pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase 
Explanation: Link reaction & TCA cycle requires 5 coenzymes: Lipoic acid and four B-complex Vitamins (B1, B2, B3, B5). Due to this reason, Thiamine (vitamin B1) deficiency results in decrease energy production (also CNS problems because Brain cells depend on this aerobic reaction) as TCA & link reaction both are responsible for energy production in cells.