This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins and Minerals, Subject name: Biochemistry
Which of the following minerals is a major component of biological membranes? 
Select and explain. 
A. Potassium, B. Sodium, C. Calcium, D. Phosphorus
D: Phosphorus
Answer: D: Phosphorus 
Explanation: Lipid bilayer is made up of phospholipids - Lecithin, Sphingomyelin, Phosphatidyl Inositol and Phosphatidyl serine. So, phosphorus is a major component of biological membranes.