All members of group 14 when heated in oxygen form oxides. There are mainly two types of oxides, i.e., monoxide and dioxide of formula MO and MO2 respectively. SiO only exists at high temperature. Oxides in higher oxidation states of elements are generally more acidic than those in lower oxidation states. The dioxides CO2,SiO2 and GeO2 are acidic, whereas SnO2 and PbO2 are amphoteric in nature. Amongst monoxides, CO is neutral.
Hence option C is the answer.