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: Physiology
Cardiac output in 1./min divided by hea rate equals: 
Select and explain. 
A. Cardiac efficiency, B. Mean stroke volume, C. Cardiac index, D. Mean aerial pressure
B: Mean stroke volume
Answer: B: Mean stroke volume 
Explanation: B i.e. Mean stroke volume