All but one describes a function of apoptosis. that is a) cell death that occurs when cells are exposed to toxins or are injured. b) maintain a balance with in the immune system by getting rid of spent immune cells. c) cells undergo cellular suicide when they receive certain cues indicating that the cell is damaged. d) occurs during embryological development to make sure that extra body tissues are not present wants embryo has developed.

The right answer is A.

Apoptosis is cell suicide, or programmed cell death (according to an established genetic program). the opposite of necrosis which is a cell death due to a toxin.

Thus, it is the apoptosis that kills the cells between the fingers during the embryonic development, to allow to dissociate them. The same phenomenon makes the caudal appendage disappear.

Apoptosis is also involved in the elimination of incompetent or useless immune cells.

Apoptosis is also used to eliminate cells that have irreparable damage to DNA (damaged telomeres), to prevent the development of cancer.