K₄[Fe(CN)₆] can be used to detect one or more out of Fe2+, Fe3+, Zn2+, Cu2+, Cd2+
A. Fe²⁺, Fe³⁺ ,
B. Fe³⁺, Zn⁺, Cu²⁺ ,
C. all but Fe²⁺
D. all but Fe²⁺