The Element Oxygen Consists of Three Naturally Occuring Isotopes: ¹⁶O

The element oxygen consists of three naturally occuring isotopes: ¹⁶O, ¹⁷O, and ¹⁸O.The atomic mass of oxygen is 16.0 amu. What can be implied about the relative abundances of these isotopes?

A) More than 50% of all O atoms are ¹⁷O.
B) Almost all O atoms are ¹⁸O.
C) Almost all O atoms are ¹⁷O.
D) The isotopes all have the same abundance, i.e.33.3%.
E) The abundances of ¹⁷O and ¹⁸O are very small.