This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
Glutamic acid is formed from which of the following amino acid? 
Select and explain. 
A. Threonine, B. Proline, C. Alanine, D. Lysine
C: Alanine
Answer: C: Alanine 
Explanation: Glutamic acid is formed by the transamination of alanine and vice versa. Alanine aminotransferase is the enzyme and pyridoxal phosphate is the coenzyme.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 201, fig.15.8.