The following compounds decolorize acidified potassium tetraoxomanganate (VII) solution EXCEPT

Explanation

Compounds that decolourize potassium permanganate (KMnO4) include unsaturated organic compounds like alkenes and alkynes, as well as reducing agents like sulphur dioxide, hydrogen sulphide, iron(II) sulfate, and sodium sulphite (Na2SO3), which readily react with the oxidizing agent KMnO4, causing a colour change from purple to colorless due to the reduction of manganese ions in the permanganate molecule. 

All the other options apart from option A are unsaturated hydrocarbons( alkenes).