Which one of the following reactions occurs in the cristae of the mitochondria?   

A. The prep reaction  
B. Glycolysis  
C. The electron transport chain  
D. The citric acid cycle  

B?

I don't know. But this may contain the answer.

http://study.com/academy/lesson/mitochondrial-christae-definition-function-quiz.html

Thanks

Actually, the correct answer is C. The electron transport chain occurs in the cristae of the mitochondria. The electron transport chain is a series of protein complexes and electron carriers located in the inner mitochondrial membrane, which is folded into structures called cristae.

To determine the correct answer, you can use your understanding of cellular respiration and the specific locations where each reaction takes place.

A. The prep reaction, also known as the pyruvate dehydrogenase reaction, occurs in the mitochondrial matrix, not in the cristae.

B. Glycolysis occurs in the cytoplasm of the cell, not in the mitochondria.

C. The electron transport chain occurs in the cristae of the mitochondria. This is where the majority of ATP production takes place during cellular respiration.

D. The citric acid cycle, also known as the Krebs cycle, occurs in the mitochondrial matrix, not in the cristae.

By considering the location where each reaction occurs, you can determine that the correct answer is C.