This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Carbohydrates, Subject name: Biochemistry
A common intermediate in the conversion of glycerol and lactate to glucose is which one of the following? 
Select and explain. 
A. Pyruvate, B. Oxaloacetate, C. Malate, D. Glucose-6-phosphate
D: Glucose-6-phosphate
Answer: D: Glucose-6-phosphate 
Explanation: The only intermediate included in the list that the pathway of gluconeogenesis from glycerol has in common with the pathway of gluconeogenesis from lactate is glucose-6-phosphate. Glycerol enters gluconeogenesis as DHAP. Therefore, it bypasses the other compounds (pyruvate, oxaloacetate, malate, and PEP) through which the carbons of lactate must pass on its pathway to glucose synthesis.