The correct option is C Mitochondrial matrix
During aerobic respiration, pyruvic acid that is produced as a result of glycolysis, is further oxidised into CO2 and water after passing through a series of reactions.
This series of reactions takes place in the matrix of mitochondria and is known as kerbs' cycle, after the name of its discoverer.
The process of glycolysis takes pace in cytoplasm, where as the Electron Transport Chain is located on the inner membrane of mitochondria.