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
TRUE regarding human heart 
Select and explain. 
A. Conduction of impulse from endocardium to inwards, B. During exercise duration of systole is reduced more than diastole, C. HR increases with parasympathetic denervation, D. Vagal stimulation decreases force of contraction
C: HR increases with parasympathetic denervation
Answer: C: HR increases with parasympathetic denervation 
Explanation: In resting state, the heart is under vagal control. But when there is vagal denervation, the sympathetic activity is unhindered and the heart rate increases.
Conduction is from endocardium to epicardium.
During exercise, the duration of diastole is more decreased than systole.
Vagal stimulation does not decrease the force of contraction.