The correct option is C a (iv) , b (i), c (ii), d (iii)
Oxides of metals are basic in nature and oxides of non-metals are acidic in nature. Whereas, oxides of metalloids are amphoteric in nature.
Therefore, Cl2O7 is an acidic oxide, BaO is a basic oxide and As2O3 is an amphoteric oxide.
Some neutral oxides are N2O,CO,NO.