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
Most potent cardiac stimulant of the following is: 
Select and explain. 
A. Adrenaline, B. Noradrenaline, C. Ephedrine, D. Salbutamol
A: Adrenaline
Answer: A: Adrenaline 
Explanation: None