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: Microbiology
[{'content': 'Pertusis toxin acts by all of the following mechanisms except ? \nSelect and explain. \nA. ADP ribosylation of proteins associated with receptors, B. Increase cyclic AMP, C. Increased calcium release from sarcoplasmic reticulum, D. Acts through G alpha subunit', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]