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 and smooth muscle contraction and relaxation is/area) Troponin (+ve)b) Myosin light chain kinasec) Ca2+d) Actine) Myosin 
Select and explain. 
A. ac, B. a, C. ab, D. bc
C: ab
Answer: C: ab 
Explanation: Troponin is absent in case of smooth muscles but present in skeletal muscles.
 
Myosin light chain kinase is involved in case of smooth muscle contraction, but not in skeletal muscles.