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
Which of the following amino acids is purely ketogenic? 
Select and explain. 
A. Phenylalanine, B. Leucine, C. Proline, D. Tyrosine
B: Leucine
Answer: B: Leucine 
Explanation: Purely ketogenic amino acid is LeucineRef: Textbook of biochemistry for medical students, seventh edition, page no: 27