$$E\,vs\,Z\,plot\,(cons\tan t\,n)\left\{ \matrix{ E - Energy\,of\,the\,stationary\,state \hfill \cr Z - atomic\,number \hfill \cr n - \Pr incipal\,quantum\,number \hfill \cr} \right.$$

The formula of energy of hydrogen like species is

$$E = - 13.6{{{z^2}} \over {{n^2}}}eV$$

$$E \propto - {{{z^2}} \over {{n^2}}}$$

For constant n, $$E \propto - {Z^2}$$

Here, E and Z has a quadratic relationship. Since the equation (proportionality) includes a negative sign, the graph of E vs Z will be a downward - opening parabola.

The graph is like an upside down U. In the given options, graph 4 is like half upside down parabola.

The shape is characteristic of negative quadratic function, where the curve opens downward, with the vertex of the parabola at the origin.

So, the answer is option (4).