The correct option is D Mitochondria
Fatty acid degradation is the process in which fatty acids are broken down into acetyl-CoA, the entry molecule for the citric acid cycle, the main energy supply of animals. Fatty acid degradation takes place within the mitochondria and requires the help of several different enzymes. In order for fatty acids to enter the mitochondria the assistance of two carrier proteins is required, Carnitine acyltransferase I and II.