The answer is; B
Rocks have naturally occurring and spontaneously radioactive atoms in them, such as carbon-14. These element isotopes decay into other types of atoms over millions of years. Therefore, by measuring the amount of these radiometric substances, and knowing the half-life of the isotopes, it is possible to postulate the age of a rock to within certain ranges of error.
The breakdown of molecules by food enzymes and acid in the stomach
Cells divide for many reasons. For example, when you skin your knee, cells divide to replace old, dead, or damaged cells. Cells also divide so living things can grow. ... Organisms grow because cells are dividing to produce more and more cells.
