This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzyme regulation, Subject name: Biochemistry
All of the following are covalent modifications of enzyme regulation EXCEPT: 
Select and explain. 
A. Phosphorylation, B. ADP Ribosylation, C. Acetylation, D. Glycosylation
D: Glycosylation
Answer: D: Glycosylation 
Explanation: Various ways of covalent modifications of enzymes are : Most common is Phosphorylation and Dephosphorylation ADP Ribosylation, Methylation, Acetylation