A Solution Contains [Ba²⁺] = 5

Multiple Choice

A solution contains [Ba²⁺] = 5.0 × 10^-5 M, [Ag⁺] = 3.0 × 10^-5 M, and [Zn²⁺] = 2.0 × 10^-7 M. Sodium oxalate is slowly added so that [C₂O₄^2-] increases.
Salt BaC₂O₄   ZnC₂O₄   Ag₂C₂O₄
Ksp 1.5 × 10^-8   1.35 × 10^-9  1.1 × 10^-11
Which one of the oxalates precipitates first?

A) BaC₂O₄
B) Na₂C₂O₄
C) ZnC₂O₄
D) Ag₂C₂O₄
E) ZnC₂O₄ and Ag₂C₂O₄ precipitate together