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
All of the given drugs are positive inotropes EXCEPT 
Select and explain. 
A. Dopamine, B. dobutamine, C. Digoxin, D. Doxepin
D: Doxepin
Answer: D: Doxepin 
Explanation: None