Considering the elements $\mathrm{F},\mathrm{Cl},\mathrm{O} \mathrm{and} \mathrm{S}$, the correct order of their electron affinity values is:

Considering the elements $\mathrm{F},\mathrm{Cl},\mathrm{O} \mathrm{and} \mathrm{S}$, the correct order of their electron affinity values is: $\mathrm{Cl}>\mathrm{F}>\mathrm{S}>\mathrm{O}$

F and Cl have more electron gain enthalpy than O and S because effective nuclear charge increases as we move from left to right in a periodic table.
In each of their respective groupings, fluorine and oxygen are the tiniest elements. The electrical configuration of the valence shell for fluorine is $2s^{2}2p^5$. The system becomes relatively unstable as a result of the intense electron-electron repulsion that results from adding another electron to the valence shell. The same holds true for oxygen. Enthalpy of electron gain for Cl>F and S>O.

Therefore, correct order is: $\mathrm{Cl}>\mathrm{F}>\mathrm{S}>\mathrm{O}$

Hence, option C is correct.