A mother and two young children are found passed out in their apartment, where a space heater is on. Emergency medical technicians suspect carbon monoxide poisoning. Why is carbon monoxide dangerous?

A. IgD: IgD is mainly a B-cell receptor on naïve B cells and is not the dominant secretory antibody in mucosal secretions or breast milk.
B. IgA: Secretory IgA is abundant in breast milk (colostrum) and mucosal secretions (tears, saliva, nasal fluid) and helps protect infants’ mucosal surfaces from pathogens.
C. IgE: IgE is involved in allergy and parasitic defense and is not the primary protective antibody in breast milk or mucosal secretions.
D. IgM: IgM is the first antibody produced in primary responses and is mainly intravascular; it is not the dominant secretory antibody passed in milk.

A. The presence of antibodies triggers the production of antigens: antibodies are produced in response to antigens, not the other way around.
B. Antibodies can be foreign cells, proteins, or other large molecules. Antigens are large proteins made by B cells: this reverses definitions: antigens are foreign molecules/cells that stimulate immune response; antibodies are proteins produced (by B cells) that bind antigens.
C. Antigens function to destroy or neutralize antibodies: antigens elicit antibody production; they do not act to destroy antibodies.
D. The presence of an antigen triggers the production of antibodies: antigens (foreign proteins, polysaccharides, cells) stimulate B cells to differentiate into plasma cells that produce specific antibodies.