Single-celled or unicellular fungi are: molds monolyathids protoplasm yeasts

The answer is yeasts.

Fungi is the kingdom of Eukaryota domain and includes unicellular organisms and multicellular organisms. Y easts are u nicellular fungi. But, some species have an ability to develop some kind of multicellular characteristics such as pseudohyphae that forms by connecting budding cells.

The answer to the question stated above is "yeasts".

Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. These yeasts evolved from multicellular ancestors with the ability to develop multicellular characteristics by forming strings of connected budding cells.