Step-by-step explanation:
Immunoglobulin M is the first antibody produced on initial exposure to an antigen. It is also known as IgM.
It occurs as a primary response to the antigens against a particular baterium or virus. It is pentavalent in nature and has ten binding sites for antigens.
Therefore, it is concluded that when the body identifies a bacterium or a virus, it releases the antibody IgM.