This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
The respiratory chain is found in which sub cellular compament? 
Select and explain. 
A. Cytosol, B. Endoplasmic reticulum, C. Golgi, D. Mitochondria
D: Mitochondria
Answer: D: Mitochondria 
Explanation: Mitochondria serve as the powerhouses of the cell. In addition to having the respiratory chain and serving as the site for oxidative phosphorylation, mitochondria also contain the enzymes of the citric acid cycle and for b oxidation of fatty acids.