* DNA (Deoxyribonucleic Acid): The genetic blueprint of life. It contains the instructions for building and maintaining an organism. All living cells, from bacteria to humans, have DNA.

* Cell Membrane: The outer boundary of a cell, controlling what enters and leaves. Found in all cells.

* Cytoplasm: The jelly-like substance within the cell membrane, where many chemical reactions occur. Found in all cells.

* Mitochondria: The "powerhouses" of the cell, producing energy (ATP). Found in most cells, but not in some specialized cells like red blood cells.

Therefore, DNA is the only option found within all cells.