multicellular organisms have better survival than their cellular counterpart. Why?

In multicellular organisms different jobs are done by different cells. Cells are more specialised. As a result if division of labour, tissues will be formed. Death of few cells does not affect the survival of multicellular organisms The cells that die are replaced by the new ones formed by the division of the surviving cells this is not true with their cellular counter part because injury to one cell could lead to the death of the organism or the cell.