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
In the krebs cycle, CO2 is released from a step catalyzed by which of the following enzyme? 
Select and explain. 
A. Isocitrate dehydrogenase, B. succinate dehydrogenase, C. Aconitase, D. Succinate thiokinase
A: Isocitrate dehydrogenase
Answer: A: Isocitrate dehydrogenase 
Explanation: Reference: Harper's Illustrated Biochemistry 31st edition Pg 151