Final answer:
In the primary immune response, IgM is the main antibody produced, which later evolves into the production of IgG in the secondary response.
Step-by-step explanation:
The antibody type that is chiefly seen in the primary immune response is IgM (Immunoglobulin M). This class of antibody is the first to be made by the body in response to an infection. IgM molecules are assembled into pentamers, meaning they can bind ten identical antigens, albeit with less stability than IgG antibodies. Although IgG is an important antibody in both late primary responses and the main antibody in secondary responses, it is IgM that is predominantly produced in the earlier stages of a primary immune response.