The addition of an oxidizing agent such as chlorine water

Question

The addition of an oxidizing agent such as chlorine water to a clear solution of an unknown compound results in the appearance of a brown color. When this solution is shaken with the organic solvent, methylene dichloride, the organic solvent layer turns purple. The unknown compound probably contains

(A) K⁺

(B) Br¯

(C) NO₃¯

(D) I¯

(E) Co²⁺