The Atomic Mass of Naturally Occurring Copper, Which Is a Mixture

The atomic mass of naturally occurring copper, which is a mixture of two isotopes, is listed as 63.546 u. This means that ,Hint: Individual atoms have a mass number which is the sum of the protons and neutrons.

A) all copper atoms found in nature have a mass that is 63.546/12.000 times as great as that of a ¹²C atom.
B) all copper atoms found in nature have a mass that is 63.546/1.0079 times as great as that of a ¹H atom.
C) some copper atoms found in nature have a mass that is 63.546/12.000 times as great as that of a ¹²C atom.
D) some copper atoms found in nature have a mass that is 63.546/1.0079 times as great as that of a ¹H atom.
E) no copper atoms found in nature has a mass that is 63.546/12.000 times as great as that of a ¹²C atom.