Which immunoglobulin provides long-term immunity during subsequent exposures to pathogens?

The choice indicating that immunoglobulin G (IgG) provides long-term immunity is accurate because IgG is the most abundant type of antibody found in the bloodstream and plays a crucial role in the immune response. It is primarily responsible for the adaptive immune system's memory, allowing the body to mount a quicker and more effective response upon re-exposure to the same pathogen.

Unlike other immunoglobulins, IgG can persist for months or even years after an initial infection or vaccination, thus providing sustained protection. It is also able to cross the placenta, offering passive immunity to the fetus during pregnancy, which adds to its role in long-term immunity. IgG's ability to neutralize toxins, opsonize pathogens (mark them for destruction), and activate the complement system enhances its effectiveness in preventing infection upon subsequent exposures.

In contrast, IgA primarily provides protection at mucosal surfaces, IgE is mainly involved in allergic responses and defense against parasitic infections, and IgM is the first antibody produced in response to an infection but does not typically provide long-term immunity because it is mainly present early during the immune response.