Which oxides form acidic solutions when added to water?

A.     \({{\text{P}}_{\text{4}}}{{\text{O}}_{{\text{10}}}}{\text{(s)}}\) and \({\text{S}}{{\text{O}}_{\text{3}}}{\text{(g)}}\) 

B.     \({\text{N}}{{\text{a}}_{\text{2}}}{\text{O(s)}}\) and \({\text{MgO(s)}}\)

C.     \({\text{A}}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{3}}}{\text{(s)}}\) and \({\text{Si}}{{\text{O}}_{\text{2}}}{\text{(s)}}\)

D.     \({\text{MgO(s)}}\) and \({\text{A}}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{3}}}{\text{(s)}}\)

A