Which statement describes the Cell Theory?

The statement that all living things are composed of cells is a fundamental principle of Cell Theory. This theory, which emerged in the 19th century through the work of scientists such as Schleiden, Schwann, and Virchow, emphasizes that cells are the basic unit of life. It asserts that every organism, whether unicellular or multicellular, is made up of at least one cell. This principle unifies all biological sciences by establishing that the cell is the structural and functional unit of all living organisms.

By contrast, the other statements do not align with Cell Theory. Cells can replicate, but that doesn't mean they do so indefinitely or that all cells are identical; in fact, cells can differentiate into many types depending on their function within an organism. Additionally, cells can indeed divide, which is a vital part of growth and reproduction in living organisms. Thus, the correct statement highlights the universal nature of cells in all forms of life.