The Atomic Mass of Naturally Occurring Cobalt, Which Exists in Nature

The atomic mass of naturally occurring cobalt, which exists in nature as a single isotope, is listed as 58.9332 u. This means that

A) all cobalt atoms found in nature have a mass that is 58.9332/12.000 times as great as that of a ¹²C atom.
B) all cobalt atoms found in nature have a mass that is 58.9332/1.0079 times as great as that of a ¹H atom.
C) some cobalt atoms found in nature have a mass that is 58.9332/12.000 times as great as that of a ¹²C atom.
D) some cobalt atoms found in nature have a mass that is 58.9332/1.0079 times as great as that of a ¹H atom.
E) no cobalt atom found in nature has a mass that is 58.9332/12.000 times as great as that of a ¹²C atom.