Elements A, B and C belong to third period of the long form of the periodic table. The nature of the oxides of A, B and C is amphoteric ,basic and acidic respectively. The correct order of the atomic numbers of these elements is

Left to right in a period non metallic character increases, acidic character of oxide increases.
'C' forms acidic oxide thus 'C' is non-metal
'B' forms basic oxide thus 'B' is metal
'A' forms amphotenic oxide thus 'A' is metalloid
Atomic number C>A>B