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: Pharmacology
Fastest acting receptor/transduction mechanism is: 
Select and explain. 
A. Adenylyl cyclase – cyclic AMP pathway, B. Phospholipase C–IP3 : DAG pathway, C. Intrinsic ion channel operation, D. Nuclear receptors
C: Intrinsic ion channel operation
Answer: C: Intrinsic ion channel operation 
Explanation: None