The dough used for making bread is fermented using baker's yeast, which consists of which of the following microbes?

Option 1 -> Baker's yeast (Saccharomyces cerevisiae) is a single-celled fungus that ferments sugars.

Option 2 -> Bacteria are prokaryotic microorganisms, not yeast.

Option 3 -> Viruses are non-cellular entities that cannot perform fermentation.

Option 4 -> Parasites depend on hosts; yeast is a free-living organism, not a parasite.

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Hence, Option 1: fungus -> Baker's yeast is Saccharomyces cerevisiae, a unicellular fungus that ferments sugars in dough, producing carbon dioxide gas that causes the bread to rise and alcohol (which evaporates during baking) -> correct