The two reactions of the citric acid cycle where CO₂ is produced are catalyzed by _________ and _________

A)isocitrate dehydrogenase; $\alpha$ -ketoglutarate dehydrogenase
B)isocitrate dehydrogenase;malate dehydrogenase
C) $\alpha$ -ketoglutarate dehydrogenase;succinate dehydrogenase
D) $\alpha$ -ketoglutarate dehydrogenase;malate dehydrogenase
E)succinate dehydrogenase;malate dehydrogenase