Identify unicellular organism(s) from the following options.
a. Lactobacilli
b. Yeast
c. Spirogyra
d. Mushroom
a and b
All bacteria including Lactobacilli are unicellular organisms.
Most fungi like mushrooms are multicellular however, yeast specifically is a unicellular fungus. Spirogyra is an example of a multicellular, green algae.