In which of the following steps of Kreb’s cycle, decarboxylation occurs.
A) Pyruvate $\to$ Acetyl CoA
B) Citric acid $\to$$\to$ Keto glutaric acid 
C) Alpha Keto glutarate $\to$ Succinic Acid
D) Malic acid $\to$Oxaloacetic  Acid

Decarboxylation takes place when citric acid (^C) is converted to alpha keto glutaric acid (5C) and when alpha keto glutaric acid (5C) is converted to succinyl CoA (4C) during kreb cycle.

Though conversion of pyruvic acid to acetyl CoA also requires decarboxylation but it is not a part of Kreb cycle.