Answer:
C. Natural abundance
Step-by-step explanation:
The percentage of natural occurrence of an isotope of an element on the planet is the natural abundance or the geonormal abundance.
- Proportions of each isotope of an element that occurs naturally is the natural abundance.
- It is represented as a percentage value.
- From the natural abundance, we can determine the relative atomic mass.
- If we know the atomic mass of each of the isotope and their abundances, it is easy to determine their relative atomic masses.