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: Physiology
Histamine is formed by ___ of histidine 
Select and explain. 
A. Methylation, B. Reduction, C. Oxidation, D. Decarboxylation
D: Decarboxylation
Answer: D: Decarboxylation 
Explanation: None