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
Enzyme  responsible  for  complete  oxidation  of glucose to CO2 and water is present in: 
Select and explain. 
A. Cytosol, B. Mitochondria, C. Lysosomes, D. Endoplasmic reticulum
B: Mitochondria
Answer: B: Mitochondria 
Explanation: Under aerobic conditions, pyruvate is taken up into mitochondria, and after oxidative decarboxylation to acetyl-CoA is oxidized to CO2 by the citric acid cycle.
Under anaerobic conditions, pyruvate is reduced by  the  NADH  to  lactate,  catalyzed  by  lactate dehydrogenase.

Harper 30th edition pg-162