Ammonium Metavanadate Reacts with Sulfur Dioxide in Acidic Solution as Follows

Ammonium metavanadate reacts with sulfur dioxide in acidic solution as follows (hydrogen ions and H₂O omitted) : xVO₃^- + ySO₂ $\rightarrow$ xVO²⁺ + ySO₄^2-
The ratio x : y is

A) 1 : 3
B) 1 : 2
C) 2 : 1
D) 3 : 1
E) 1 : 1