This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
The following is responsible for relaxation 
Select and explain. 
A. Actin, B. SERCA, C. Both, D. None
B: SERCA
Answer: B: SERCA 
Explanation: SERCA is a calcium channel protein It causes relaxation by storing calcium Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:86,87