All BUT ONE describes a function of apoptosis. That is ___. ( a. cells undergo cellular suic*de when they receive certain cues indicating that the cell is damaged ) ( b. maintain a balance within the immune system by getting rid of spent immune cells ) ( c. cell death that occurs when cells are exposed to toxins or are injured ) ( d. occurs during embryological development to make sure that extra body tissues are not present once the embryo has developed )