Select the correct statement about radioactivity:

A、external conditions cannot affect the type of nuclear radiation (α, ß or γ)
B、it does not depend on whether the atom is a part of an element or a compound
C、radioactivity can also be characterized by half-life, the time in which the number of nuclei of radioactive atoms decreases to one half of their original number
D、it is an attribute of atomic nuclei
E、it is a spontaneous decay of atomic nuclei of some elements accompanied by the emission of nuclear radiation