This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory chain, Subject name: Biochemistry
Living cells require which of the following as a component of ATP, NAD, NADP and flavins 
Select and explain. 
A. Organic sulfar, B. Magnesium ion, C. Inorganic phosphates, D. Ferrous ion
C: Inorganic phosphates
Answer: C: Inorganic phosphates 
Explanation: The vital role of inorganic phosphate, ADP, ATP, and NAD(H), and ultimately identified the phosphorylated sugars and the chemical reactions and enzymes (Gk "in yeast") that conve glucose to pyruvate (glycolysis) or to ethanol and CO2 (fermentation).Subsequent research in the 1930s and 1940s identified the intermediates of the citric acid cycle and of urea biosynthesis and provided insight into the essential roles of ceain vitamin-derived cofactors or "coenzymes" such as thiamin pyrophosphate, riboflavin, and ultimately coenzyme A, coenzyme Q, and cobamide coenzymesRef: Harper&;s biochemistry, 30th edition, page no: 3