The pair that does NOT require calcinations is

A

$$\text{ZnO}$$ and $$\text{MgO}$$

B

$$\text{Fe}_2\text{O}_3$$ and $$\text{CaCO}_3 \cdot \text{MgCO}_3$$

C

$$\text{ZnO}$$ and $$\text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O}$$

D

$$\text{ZnCO}_3$$ and $$\text{CaO}$$