Find the empirical formula of a compound containing Fe, S and $O$ in mass retio $7.6: 12$.
(A) $\mathrm{FeSO}_{4}$
(B) $\mathrm{Fe}_{2} \mathrm{S}_{2} \mathrm{O}_{3}$
(C) $\mathrm{Fe}_{2} \mathrm{S}_{2} \mathrm{O}_{7}$
(D) $\mathrm{Fe}_{2} \mathrm{S}_{3} \mathrm{O}_{12}$