Amphoteric oxides are compounds that can act as both acidic and basic oxides, depending on the conditions. They can react with both acids and bases to form salts and water.

i. SnO2 and SiO: Both tin(IV) oxide (SnO2) and silicon monoxide (SiO) are amphoteric oxides. They can react with both acids and bases.

ii. SiO2: Silicon dioxide (SiO2) is not an amphoteric oxide. It is primarily acidic in nature and does not exhibit amphoteric properties.

iii. SnO2 and PbO2: Tin(IV) oxide (SnO2) is amphoteric, but lead dioxide (PbO2) is not amphoteric. It primarily exhibits acidic properties.

iv. CO and SiO: Carbon monoxide (CO) is not an amphoteric oxide. It is primarily considered a neutral oxide. Silicon monoxide (SiO) is amphoteric.

Therefore, the correct option containing only amphoteric oxides is (i) SnO2 and SiO.