The pair that does NOT require calcination is :

$\mathrm{ZnO}$ and $\mathrm{MgO}$

$\mathrm{ZnO}$ and $\mathrm{Fe}_{2} \mathrm{O}_{3} \cdot x \mathrm{H}_{2} \mathrm{O}$

$\mathrm{ZnCO}_{3}$ and $\mathrm{CaO}$

 $\mathrm{Fe}_{2} \mathrm{O}_{3}$ and $\mathrm{CaCO}_{3} \cdot \mathrm{MgCO}_{3}$