Silver's weighted average atomic mass is 107.86, leading one to assume that its most abundant isotope would be silver-108 (or 108Ag). Silver does have two naturally occurring isotopes, but 108Ag is not one of them. Which of the following best explains this phenomenon?

a) When one is determining atomic masses in the laboratory, a significant amount of experimental error occurs.
b) When the two isotopes of silver experience radioactive decay, their most abundant end product is silver-108.
c) Although silver-108 is not naturally occurring, it is synthetically created in large quantities to meet consumer demands.
d) The two silver isotopes have atomic masses of approximately 107 and 109 and are found in similar abundance in nature.