Natural Killer (NK) cells

A) are a type of macrophage.
B) are a type of plasma cell.
C) secrete enzymes that kill tumor or virus-infected cells.
D) are derived from B cells.
E) promote inflammation.

Natural Killer (NK) cells are part of the innate immune system and have the ability to kill tumor cells or cells infected with viruses by secreting enzymes that lead to the target cell's death. They are not macrophages, plasma cells, derived from B cells, nor do they primarily promote inflammation.