If two are atoms are isotopes of the same elements the atoms must have

The atoms must have the same number of protons.

Isotopes mean that there are atoms with the same number of protons, but a different number of neutrons.

For example, carbon 12 and carbon 14 are isotopes. Both have 6 protons, but carbon 12 has 6 neutrons, whereas carbon 14 has 8.

i wish i could but this one is weird give me abc and i can solve it.

c) should be the answer.