Before introducing $FeO$ in blast furnace , it is converted to $Fe_2O_3$ by roasting so that

Question

$(a)\;\text{It may not be removed as slag with silica} \\(b)\;\text{It may not evaporate in the furnace } \\(c)\;\text{Presence of it may increase the m.pt. of charge } \\ (d)\;\text{ None.}$