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. ER
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.

(Ref: Harper Ed. 29th pg173, Ed 30th pg 172)