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
All are effects of sympathetic stimulation, EXCEPT 
Select and explain. 
A. Increased conduction velocity, B. Increased heart rate, C. Increased refractory period, D. Increased contractility of heart
C: Increased refractory period
Answer: C: Increased refractory period 
Explanation: When sympathetic system is activated, the refractory period is decreased.