Which two notation represent different isotopes of the sam element?

The two with the same proton number. An isotope is an atom with the correct number of protons as the element but has a different number of neutrons. That means it can't be 3 or 4 because they use two different elements. 1 and 2 both have the correct proton number for each element but they have different atomic mes and so are isotopes of each other.