This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
All the following amino acids contain a hydroxyl group, Except ? 
Select and explain. 
A. Serine, B. Lysine, C. Threonine, D. Tyrosine
B: Lysine
Answer: B: Lysine 
Explanation: Amino acids with side chains containing Hydroxyl groups: 1.Serine 2.Threonine 3.Tyrosine Lysine is an amino acid with the side chain containing Basic groups Reference: Explanation: Harper's Biochemistry; 30th edition; Chapter 3; Amino acids and Peptides