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: Biochemistry
Cardiolipin is an impoant component of which of the following: 
Select and explain. 
A. Mitochondria, B. Cell membrane, C. Ribosome, D. All of the above
A: Mitochondria
Answer: A: Mitochondria 
Explanation: Phosphatidic acid is a precursor of phosphatidyl-glycerol which, in turn, gives rise to cardiolipin. This phospholipid is found only in mitochondria and is essential for mitochondrial function. Ref: Harper 28th edition, chapter 16.