This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid, Electrolyte, Subject name: Pediatrics
[{'content': 'Maximum concentration of plasma calcium exist as - \nSelect and explain. \nA. Complexed to phosphate, B. Complexed to citrate, C. Bound to plasma albumin, D. Ionized form', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Plasma calcium exist as - 50 % - Biologically active ionized form 45% - Bound to plasma proteins (mainly albumin) 5% - Complexed to phosphate & citrate', 'role': 'assistant'}]