Ashbya gossypii is a
A. Fungus producing riboflavin
B. Fungus forming B12
C. Actinomycetes excreting Vitamin A
D. Bacterium forming antibodies

Hint: Ashbya gossypii is also called Eremothecium gossypii, and it is the filamentous fungus that is closely related to the yeast, but it grows in a filamentous way, where it was originally isolated from cotton as and pathogen by scientist Ashby and Nowell in 1926.

Complete answer:
> This fungus has two phases, where its life cycle starts with spore form, which has isotropic growth and has the wild type of germination and it forms the germ bubble.
> After the spore form, it is followed by apical growth, extending 2 germ tubes, in succession on opposite sides of the germ bubble.
> This is a type of fungi the maturation occurs by apical branching.
> These fungi have special importance where this Ashbya gossipy is used as a model to see regulatory effects of different forms and is also used to govern the functional difference between the filamentary growth and yeast growth.
> This fungus causes the disease in cotton where it mainly affects the hair cells in cotton balls.
> Apart from pathogens, this Ashbya gossypii was recognized as a natural overproduction of riboflavin that is vitamin B2, where this riboflavin protects it’s spores against the ultraviolet light.
> So this fungus is a very interesting organism for the industries where genetically modified strains are still used to produce this vitamin.

So as it is the natural producer of the vitamin riboflavin, the correct option is A.

Note: So the filamentous fungus ashbya gossypii has long been considered a paradigm of the white Bio-technology on the concern of riboflavin production, this lead to improve in industries and it shows the metabolism of how the riboflavin is produced, and where it can be used for commercial purposes.