The Body Uses Atoms in Different Ways to Accomplish Different

The body uses atoms in different ways to accomplish different tasks.For example,one portion of the body's calcium supply strengthens bones,whereas another portion combines with proteins to stimulate blood clotting after tissue injury.Which of the statements that follow provides the most logical chemical explanation of calcium's ability to perform such different functions?

A) There are many different isotopes of calcium,and the most reactive isotope is found in the bone.
B) The bone contains calcium salts,which are less reactive than the calcium ions found in the blood.
C) The calcium in blood is a more reactive form of the atom and therefore has fewer protons than the calcium in bone.
D) The calcium in blood has a lighter atomic mass than the calcium in bone and is in a more reactive form.