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
Following modification occurs in Gs subunit which leads to watery diarrhea in cholera 
Select and explain. 
A. ADP ribosylation, B. ATP-ADP transfer, C. Phosphorylation, D. Dephosphorylation
A: ADP ribosylation
Answer: A: ADP ribosylation 
Explanation: A i.e. ADP ribosylation