The correct option is A Propionibacterium
Propionibacterium is a Gram-positive, non-motile bacterium that plays an important role in the creation of Emmental cheese, and to some extent, Jarlsberg cheese, Leerdammer and Maasdam cheese. Its concentration in Swiss-type cheeses is higher than in any other cheese. It is this Propionibacterium that is responsible for the holes in Swiss cheese. Through the process of consuming the lactic acid, the bacteria produces acetate, propionic acid, and carbon dioxide as a by product.