Are a component of the immune system that are able to destroy cancer cells by deploying toxins into infected cells as a means of killing them. in this role they are cytotoxic – that is, "cell killing."

Natural killer cells

Explanation:

Natural killer cells (also known as NK cells, K cells, and killer cells) are a type of lymphocyte (a white blood cell) and a component of the innate immune system.  These cells have the function of destroying tumor cells, cancer cells, virus infected cells and any kind of foreign material. The action of these cells is called the Nonspecific Immune Response.

These cells were first identified in 1975, were labeled as Natural Killers for their cytotoxic activity against tumor cells of different lineages, without the need for prior recognition of a specific antigen, contrary to the functioning of T lymphocytes.

answer: a. a gene that causes a specific trait.