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
The difference between skeletal an smooth muscle contraction and relaxation is/are: 
Select and explain. 
A. Troponin (+ve), B. Myosin light chain kinase, C. Ca+2, D. Actin
A: Troponin (+ve)
Answer: A: Troponin (+ve) 
Explanation: A i.e. Troponin (+ve)