This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
All are involved in cardiac conduction pathway except: 
Select and explain. 
A. SA node, B. Purkinje fibers, C. Bundle of His, D. Sarcomere
D: Sarcomere
Answer: D: Sarcomere 
Explanation: Ans: D (Sarcomere) Ref: Ganong's Review of Medical Physiology. 21st ed.Explanation:Cardiac Conduction PathwaySA nodeAV nodeBundle of HisLeft and right bundle branchPurkinje fibres