Adding One Neutron to the Nucleus of an Atom

Multiple Choice

Adding one neutron to the nucleus of an atom

A) converts it to an isotope of the same element.
B) increases its atomic mass by two units,but does not change its atomic number.
C) increases its atomic number by one unit but does not change its atomic mass.
D) does not change either its atomic number or its atomic mass.
E) converts it to an atom of a different element.