Element A exists in three isotopic forms with masses of 21.0, 25.0 and 26.0 amu respectively. Element B also exists in three isotopic forms with mass of 22.0, 24.0 and 26.0 amu respectively. Is it true that:
a. none of the above
b. element A has a higher atomic mass than B
c. element B has a higher atomic mass than A
d. Element A and element B have the same atomic masses since the sums of their isotopic masses are equal