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
Which one of the following is synthesized from an essential amino acid? 
Select and explain. 
A. Alanine, B. Glutamate, C. Proline, D. Tyrosine
D: Tyrosine
Answer: D: Tyrosine 
Explanation: Tyrosine is formed from phenylalanine.