The correct option is (d) S. bayanus
Easiest explanation: Saccharomyces bayanus is not reclassified into Saccharomyces cerevisiae as it has remained unscathed by taxonomic changes. Saccharomyces tubidans, Saccharomyces ellipsoideus, Saccharomyces willianus, Saccharomyces diastaticus are now reclassified as Saccharomyces cerevisiae.