<prompt> Answer this question truthfullyDuring the secondary response to an antigen, what is the main immunoglobulin produced as an antibody?  <response>: <reason> The main immunoglobulin produced as an antibody during the secondary response to an antigen is IgG. The secondary response is a faster and more robust immune response that occurs upon re-exposure to an antigen that the immune system has previously encountered. During the secondary response, memory B-cells are activated and differentiate into plasma cells that produce large amounts of IgG antibodies. IgG is the most abundant immunoglobulin in the bloodstream and plays a critical role in the immune defense against pathogens by binding to and neutralizing them, as well as promoting their clearance by other immune cells. 