Select all sentences with acceptable agreement for neither in contemporary standard British English.
Neither of the two keys does opens the cabinet.
Neither of the two keys do opens the cabinet.
Neither of the two keys does open the cabinet.✓Bonne réponse
Neither of the two keys do open the cabinet.✓Bonne réponse
Explication
Neither of plus the plural group two keys permits both formal singular does and common informal plural do. In either construction the lexical verb after the auxiliary stays in the base form open, so adding -s to opens incorrectly marks agreement twice.