The correct IUPAC name of the compound
6-Ethyl- 1 -methyl-4-oxohept-6-ene- 1 -sulphonic acid
7-Ethyl-5-oxooct-7-ene-2-sulphonic acid
2-Ethyl-7-sulphooct- 1 -ene-4-one
7-Methylene-5-oxononane-2-sulphonic acid
−SO3H is higher in priority.