Active immunization is that which occurs as a result of the immune response of the affected individual. Passive immunization is the passing of antibodies from one entity to another, such as a pregnant mother who passes antibodies through the placenta to the fetus. Artificial immunization occurs when one is exposed to the antigen of the infection without having to experience the infection. The antigen can be a weakened or dead form of the microbe. Natural immunity is achieved when one is infected by a live form of the microbe. In both natural and artificial immunity, the immune system generates antibodies and memory cells to fight off future infections.

In blood typing, the concern is avoiding the administration a blood transfusion that will be attacked by the body's immune system. For each antigen not present on the recipient's blood cells, there will be an antibody present in their blood stream. Therefore, someone who has type A blood will have an "anti-B" antibody. A transfusion of blood presenting the B antigen would be attacked and rejected by the type A individual's body. The Rh group (+/-) works similarly. Those who are Rh negative will have an antibody present to attack blood cells with the Rh group. Similarly, if someone is is Rh positive, there will be no Rh antibodies in his or her body and he or she could accept either Rh- or Rh+ blood. The patient in this question has type AB- blood, so he or she has no antibodies except for those that bind to Rh-positive blood. Therefore, all Rh-negative blood types are acceptable. (Type O blood signifies that the blood cells have no antigens present.)

Antibodies are made by B-cells, not T-cells. Monoclonal antibodies, as their name implies, are produced by a single clone of B-cells. In other words, a single B-cell is provoked to divide, producing a clone of identical cells. These cells then crank out one single type of antibody. These are monoclonal antibodies. Monoclonal antibodies only strongly recognize and bind to one specific antigenic site. The hCG molecule, being a polypeptide, may have multiple antigenic sites that can be recognized by antibodies, but a given set of monoclonal antibodies only recognizes one of these sites.

IgG (exists as a monomer in the blood) and IgE are both small enough to cross the placenta however, IgE is present in very low levels in the plasma.

IgE is the subclass of immunoglobulins that plays a critical role in the allergy response. IgE binds to allergens which in turn bind to Fc receptors on the mast cells, triggering the release of numerous inflammatory mediators, including histamine.

T cells originate from hematopoietic stem cells in the bone marrow and migrate to the thymus where they undergo maturation.

The mechanisms of antibody-mediated antigen disposal occur in the order of neutralization, agglutination, and opsonization. During the process of neutralization, antibodies block pathogenic activity. During agglutination, antibody molecules aggregate multiple pathogens. Finally, during opsonization phagocytes engulf pathogens bound to antibodies. 

TLR7 recognizes single-stranded RNA while TLR9 recognizes DNA, TLR4 recognizes lipopolysaccharide from gram-negative bacteria, TLR5 recognizes flagellin, and TLR3 recognizes double-stranded RNA.

MHC-I on antigen-presenting cells (such as dendritic cells and macrophages) presents antigen to CD8+ T cells. MHC-II presents antigen to CD4+ T cells.

Out of all of the possible choices, only dendritic cells can process and present antigen to T cells. B cells and macrophages are other possible cell types that can be antigen-presenting cells.