Which of the following oxides is amphoteric in character?

The nature of oxides depends on the metallic or non-metallic character of the element:$\text{CaO}$: Calcium is an alkaline earth metal. Its oxide is basic.${\text{CO}}_2$: Carbon is a non-metal. Its oxide is acidic.${\text{SiO}}_2$: Silicon is a metalloid, but its oxide is primarily acidic.${\text{SnO}}_2$: Tin (Sn) is a metal that can react with both acids and bases. Therefore, ${\text{SnO}}_2$ is amphoteric.