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
Amino acid used in Carnitine synthesis is which of the following? 
Select and explain. 
A. Alanine, B. Lysine, C. Arginine, D. Tyrosine
B: Lysine
Answer: B: Lysine 
Explanation: Carnitine is a quaternary ammonium compound biosynthesized from the amino acids lysine and methionine. In living cells, it is required for the transpo of fatty acids from the cytosol into the mitochondria during the breakdown of lipids for the generation of metabolic energy. It is widely available as a nutritional supplement.