Unsaturation (Baeyer's test) involves decolorization of the reagent, represented by discharge of color (IV).
Alcoholic groups (Ceric ammonium nitrate test) produce a red color (I).
Aldehyde groups (Tollen's reagent) produce a characteristic silver mirror effect (II).
Phenolic groups (FeCl₃ test) produce a violet or pink color (III).
The correct matching is A-IV, B-I, C-II, D-III.