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 of the following is a dipeptide? 
Select and explain. 
A. carnosine, B. Glutathione, C. Glucagon, D. β-Lipoprotein
A: carnosine
Answer: A: carnosine 
Explanation: Carnosine is a dipeptide, formed by combination of beta alanine and histidine. Carnosine is a major constituent of muscles. It can activate myosin contraction. Hydrolysis of carnosine to beta alanine and histidine is done by carnosinase. Inherited deficiency of this enzyme will lead to carnosinuria.
Reference: Vasudevan 7th  ed, pg 215