The answer is nucleic acid
I believe it's A. because the bone matrix is where it goes, therefore the bone matrix is already there. it just maintains it
Dawn is correct.
When drugs are absorbed, it goes into the blood stream plasma. From there it will first go into the interstitial fluid. It will accumulate in the interstitial fluid and cross the membrane of the cell, then to the tissues, and lastly the organs.
According to theories concerning the origin of life, the atom is likely choice for the basic element of all living things because it :
B. Is relatively stable and can form four covalent bonds
This bonds will signify stability.
hope this helps