This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Bio-Chemistry), Subject name: Biochemistry
[{'content': 'The Second most important intracellular cation is \nSelect and explain. \nA. Magnesium, B. Calcium, C. Sodium, D. Iron', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (A) Magnesium # MAGNESIUM is the second most important intracellular divalent cation and is involved in a variety of metabolic processes including glucose metabolism, ion channel translocation, stimulus-contraction coupling, stimulus secretion coupling, peptide hormone receptor signal transduction.> Normal concentrations of extracellular magnesium and calcium are crucial for normal muscular activity.', 'role': 'assistant'}]