This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
The following is a regulatory protein of muscle 
Select and explain. 
A. Actin, B. Myosin, C. Troponin, D. All
C: Troponin
Answer: C: Troponin 
Explanation: Troponin and tropomyosine are the regulatory proteins of the muscle Ref:Guyton and Hall textbook of medical physiology 12th edition, page number:89