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
Normal AV delay of 0.1 seconds is due to: 
Select and explain. 
A. Decrease in amplitude of firing, B. Resistance offered by myocytes, C. Decrease in number of gap junctions, D. Lack of tight junctions
C: Decrease in number of gap junctions
Answer: C: Decrease in number of gap junctions 
Explanation: AV node conduction velocity is lowest because of: Less number of gap junctions, small diameter fibers and slow type AP.