Answer:
d and e - Sodium and antimony
Explanation:
The atomic numbers remain the same, while the mass numbers change (because neutrons are being added or taken away).
sodium has an atomic number of 19 and a mass number of 39 - in d, it has an atomic number of 19 but a mass number of 40. therefore, it is an isotope
antimony has an atomic number of 51 and a mass number of 121.60 - in e, it has an atomic number of 51, but a mass number of 123. therefore, it is an isotope
