The correct answer is option 2: Fungi.

Yeast is a type of fungus. Fungi are eukaryotic organisms that are characterized by their filamentous structures called hyphae. Yeast, however, is a unicellular fungus. It reproduces asexually by budding, where a smaller cell forms from the parent cell and eventually separates.

Bacteria (option 1) are prokaryotic microorganisms that have a different cellular structure from fungi. Algae (option 3) are photosynthetic organisms that can be found in aquatic environments, and they are not closely related to fungi. Bryophytes (option 4) are small, non-vascular plants like mosses and liverworts, which also belong to a different kingdom than fungi.

Therefore, yeast is classified as a fungus, making option 2 the correct answer.