Which component of the immune system is primarily responsible for targeting and destroying infected cells?

The component of the immune system that is primarily responsible for targeting and destroying infected cells is T-cells. T-cells, particularly cytotoxic T-cells, play a crucial role in identifying and attacking cells that have been infected by pathogens, such as viruses. When activated, these T-cells can directly kill infected cells by recognizing specific antigens presented on their surface. This targeted response is essential for controlling and eliminating infections from the body.

While other components, like macrophages, also play important roles in the immune response—such as engulfing and digesting pathogens—they do not specifically target infected cells in the same manner as T-cells. B-cells and plasma cells are primarily involved in the production of antibodies, which bind to free pathogens rather than directly attacking infected cells. Thus, T-cells are central to the cell-mediated immune response, making them the correct choice for this question.