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
An ultrashort acting β–blocker devoid of partial agonistic or membrane stabilizing action is: 
Select and explain. 
A. Esmolol, B. Timolol, C. Atenolol, D. Pindolol
A: Esmolol
Answer: A: Esmolol 
Explanation: None