Final answer:
A. immune surveillance.
The function of scanning the body for tumor antigens by T cells and natural killer (NK) cells is known as immune surveillance, involving the destruction of abnormal or infected cells by the immune system.
Step-by-step explanation:
The function of T cells and natural killer (NK) cells in scanning the body for tumor antigens is aptly known as immune surveillance. T cells, especially the cytotoxic T cells, are part of the adaptive immune system and play a crucial role in the cell-mediated immune response by targeting and destroying virally infected or tumor cells. NK cells, part of the innate immune system, complement this activity by identifying and destroying cells that display abnormal or foreign markers including those infected with viruses or transformed into cancer cells. These functions are critical for controlling infections and preventing cancer progression. Therefore, the answer to the question is A. immune surveillance.