Which statement is true regarding the cell theory?

The cell theory is a fundamental concept in biology that states that all living organisms are composed of one or more cells, the cell is the basic unit of life, and cells arise only by the division of pre-existing cells.

Therefore, the statement that cells are the smallest units of life means that all living things, from the simplest unicellular organism to the most complex multicellular organism, are composed of cells. Cells are the building blocks of life, and they are responsible for carrying out all the processes necessary for an organism's survival.