Answer:
the correct answer is- other cells.
Step-by-step explanation:
Cell theory was given by Matthias Schleiden and Theodor Schwann in 1839 which states that all the living things on the planet earth is composed of cells and these cells are the smallest, basic and functional unit of life.
Cell theory also states that a preexisting cell is responsible for the production of new cell which was early thought that new cells comes from non- living matters.
Therefore cell theory proved that new cells come from other cells that are already existing in the world. In eukaryotes, cells divide by the process of mitosis and meiosis and in prokaryotes like bacteria cell divide through binary fission and give rise to new cells.