Explanation

(d)
The electron affinities of some of the elements of second period ($ie,$ N, O, F, etc) are however, lower than the corresponding element ($ie$, P, S, Cl, etc) of the third period. This is due to the reason that the elements of second period have the smallest atomic size amongst the elements in their respective groups. As a result, there are considerable electron-electron repulsion within the atom itself and hence, the additional electron is not accepted with the same ease as is the case with the remaining elements in the same group