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