Each of the following oxides is added to separate equal volumes of distilled water. Which of the following is the most acidic oxide?

A.     ${{\text{P}}_{\text{4}}}{{\text{O}}_{{\text{10}}}}{\text{ }}$

B.     ${\text{S}}{{\text{O}}_{\text{3}}}$

C.     ${\text{C}}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{7}}}$

D.     ${\text{Si}}{{\text{O}}_{\text{2}}}$

C