The correct decreasing order of priority for the functional groups of organic compounds in the IUPAC system of nomenclature is

−COOH, −SO₃H, −CONH₂, −CHO

−SO₃H, −COOH, −CONH₂, −CHO

−CHO, −COOH, −SO₃H, −CONH₂

−CONH₂, −CHO, −SO₃H, −COOH

Solution

−SO₃H, −COOH, −CONH₂, −CHO