LIFE SCIENCE

Detailed explanation-1: -IgG is synthesized mostly in the secondary immune response to pathogens. IgG can activate the classical pathway of the complement system, and it also is highly protective. The four subclasses of IgG include IgG1, IgG2, IgG3, and IgG4.

Detailed explanation-2: -The primary immune responses to MV, initially IgM antibody, type 1 CD4 and CD8 + T-cell responses, followed by neutralizing IgG antibody, are completely effective in controlling viral replication and resolution of the infectious process.

Detailed explanation-3: -IgM is specialized to activate complement efficiently upon binding antigen. IgG antibodies are usually of higher affinity and are found in blood and in extracellular fluid, where they can neutralize toxins, viruses, and bacteria, opsonize them for phagocytosis, and activate the complement system.