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
What is the counterpart of troponin in smooth muscles 
Select and explain. 
A. Nebulin, B. Calsequestrin, C. Calmodulin, D. Titin
C: Calmodulin
Answer: C: Calmodulin 
Explanation: In skeletal muscle Ca2+ binds to Troponin-C. Likewise, in smooth muscle Ca2+ binds to Calmodulin and activates myosin light chain Kinase.