Which element, if combined with sulfur, will have the greatest attraction for the sulfur electrons? P Se I

I (iodine)

Generally electron affinity increases from left to right across a period. Thus P (to the left of S in the same period) has a lower electron affinity thens S

And electron affinity decreases as you go down a group. Thus Se (below S in the same group) has a lower electron affinity then S.

Iodine, is in group 7A (or 17) which is to the right of group 6A (or 16), where sulfur lives). It has a higher electron affinity then S.

Google electron affinity for tables showing what an elements actualy affinity is.