Answer:
(B) preparatory reaction - cristae of mitochondria
Explanation:
The oxidative decarboxylation of pyruvate into acetyl-CoA is also called preparatory reaction.
Glycolysis occurs in cytoplasm and forms two molecules of pyruvate from one molecule of glucose. The transport proteins transport pyruvate from cytoplasm to the matrix of mitochondria.
Pyruvate dehydrogenase enzyme complex is present in mitochondria which carry out oxidative decarboxylation of pyruvate and forms one molecule of acetyl CoA from each pyruvate molecule.