Which of the following isnot an example of an important inorganic substance necessary for normal human physiology? Select one:
a. Calcium ions are important components of cellular communication.
b. The sugar-phosphate backbone of DNA form from covalent bonds between nucleotides.
c. Oxygen is the final electron acceptor in cellular respiration, the process that generates much of the ATP in cells.
d. Iodide ions are important components of certain hormones in the body.