Which can readily respire without oxygen?

Answer: Option B

Saccharomyces can readily respire without oxygen.
Saccharomyces is a genus of fungi that includes many species of yeasts. They are unicellular and saprotrophic fungi.
Colonies of Saccharomyces grow rapidly and mature in three days. They are flat, smooth, moist, glistening or dull, and cream in colour.
It is widely used in making bread, wine, and beer, through the process of fermentation that does not require oxygen.