An unknown gaseous element X produces the following PES data.
Binding energy (MJ mol⁻¹) Relative peak height
0.50 2
0.80 2
3.2 6
11 2
Assuming the two lowest-binding-energy peaks correspond to valence electrons, what is the most probable oxidation state of the most stable ion formed by element X?
a) +3
b) +4
c) +2
d) −2