What type of hypersensitivity reaction could cause hemolysis of red blood cells following a transfusion?

The correct choice relates to Type II hypersensitivity reactions, which are characterized by the immune system's response against specific cell surface antigens. In the context of a transfusion, if the recipient's immune system recognizes the donor red blood cells as foreign due to the presence of incompatible antigens, it can lead to the activation of complement and subsequent destruction of those cells. This direct attack on the red blood cells is mediated by IgG or IgM antibodies that bind to the antigens on the transfused cells, triggering hemolysis.

In contrast, Type I hypersensitivity involves an immediate allergic reaction mediated by IgE antibodies and is typically associated with allergic reactions like asthma or anaphylaxis, not hemolysis. Type III hypersensitivity is characterized by immune complex deposition, leading to inflammation and tissue damage, but it does not primarily cause direct cell lysis as seen in transfusion reactions. Type IV hypersensitivity is a delayed-type reaction mediated by T cells and often involves contact dermatitis or graft-vs-host disease, which are not related to the immediate destruction of red blood cells following a transfusion.

Thus, Type II hypersensitivity correctly explains the hemolysis of red blood cells due to transfusion reactions associated with antibody-antigen interactions.