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
114-biopterin (tetrahydrobiopterine) is required for metabolism of ? 
Select and explain. 
A. Arginine, B. Lysine, C. Phenylalanine, D. Tryptophane
C: Phenylalanine
Answer: C: Phenylalanine 
Explanation: Ans. is 'c' i.e., Phenylalanine