Before introducing $\mathrm{FeO}$ in blast furnace, it is converted to ${\mathrm{Fe}}_2{\mathrm{O}}_3$ by roasting so that:

Before introducing$\mathrm{FeO}$ in a blast furnace, it is converted to ${\mathrm{Fe}}_2{\mathrm{O}}_3$ by roasting so that it may not be removed as slag with silica.

With silica and ${\mathrm{SiO}}_2, \mathrm{FeO}$ produces slag.

The reaction is as follows:

$\mathrm{FeO}+{\mathrm{SiO}}_2\to {\mathrm{FeSiO}}_3$

Hence, option A is correct.