This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Smooth muscle cell membrane is 
Select and explain. 
A. Sarcoplasm, B. Sarcolemma, C. Sarcomere, D. Sarcoplasmic reticulum
B: Sarcolemma
Answer: B: Sarcolemma 
Explanation: Protein kinase C, commonly abbreted to PKC (EC 2.7.11.13), is a family of protein kinase enzymes that are involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins, or a member of this family.