Define Immune Surveillance

Define immune surveillance.

A) Immune surveillance the normal filtering of lymph through lymph nodes to detect abnormal cells.
B) Immune surveillance is the constant filtering of blood in the kidneys to detect abnormal cells.
C) Immune surveillance is the constant circulation of available antibodies to attack pathogens.
D) Immune surveillance is the constant monitoring of normal tissues by NK cells sensitive to abnormal antigens on the surfaces of cells.
E) Immune surveillance is the constant monitoring of normal tissues by activated cytotoxic T cells.