This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
Phase I blocker is 
Select and explain. 
A. Suxamethonium, B. Atracurium, C. Gallamine, D. D-Tubocurare
A: Suxamethonium
Answer: A: Suxamethonium 
Explanation: The kind of depolarizing block produced by succinyl choline is phase I block. ref: KD Tripathi 8th ed.