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
[{'content': 'The difference between skeletal an smooth muscle contraction and relaxation is/are: \nSelect and explain. \nA. Troponin (+ve), B. Myosin light chain kinase, C. Ca+2, D. Actin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Troponin (+ve)', 'role': 'assistant'}]