This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
NAD+ is reduced to NADH + H+ by dehydrogenases of all the following substrates, Except 
Select and explain. 
A. Pyruvate, B. Glyceraldehyde-3-phosphate, C. Malate, D. Succinate
D: Succinate
Answer: D: Succinate 
Explanation: Reference: Harper&;s Biochemistry; 30th edition; Chapter 8; Enzyme kinetics