Question

which is a part of the cell theory?
cells come from pre - existing cells
cells have a nucleus
organisms with one cell must be seen with a microscope
organisms must have more than one cell to live

Explanation:

Cell theory states that all living things are made of cells, cells are the basic unit of life, and cells come from pre - existing cells. The option "cells come from pre - existing cells" aligns with this theory. Cells having a nucleus is not a universal part of cell theory (prokaryotic cells lack a nucleus). Organisms with one cell (unicellular organisms) can be seen without a microscope in some cases (e.g., some large single - celled algae). Also, there are single - celled organisms that can live independently.

Answer:

cells come from pre - existing cells