Which of the following is Cold agglutinin?

IgM cold-reacting antibodies readily agglutinate RBC and are called cold agglutins. Antibodies that react with polysaccharide antigens are usually IgM and bind antigen better at temperature lower than 37 degree celsius, hence the name cold-reactive antibodies. Uncommonly, the antibody is IgG (the Donath-Landsteiner antibody of paroxysmal cold hemoglobinuria). Ref:Harrison's Principles of Internal Medicine, 16th Edition, Pages 612-13