SnO₂ is reduced to metallic Sn on smelting oxide with anthracite, limestone and sand. In this. function of sand is :

$Sn{O}_2$ is reduced to metallic Sn on smelting oxide with anthracite, limestone and sand. The function of sand is to acts as a flux and removes basic impurities such as slag.

Sand eliminates fundamental impurities such as slag.

$\underset{\text{ Acidicflux }}{{\mathrm{SiO}}_2}+\underset{\text{ Basicgangue }}{\mathrm{FeO}}\to \underset{\text{ Slag }}{{\mathrm{FeSiO}}_3}$

Thus, the functions of sand are represented by both (a) and (b).

Hence, option C is correct