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: Pathology
Histamine is formed by of histi dine 
Select and explain. 
A. Methylatin, B. Reduction, C. Oxidation, D. Carboxylation
D: Carboxylation
Answer: D: Carboxylation 
Explanation: D i.e. Carboxylation