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: Unknown
Digitalis does not affect which parameter of heart - 
Select and explain. 
A. Heart rate, B. Contractility, C. Coronary blood flow, D. None of the above
D: None of the above
Answer: D: None of the above 
Explanation: Ans. is 'D ' i.e., None of the above