Question

which part of the cell theory is best explained by studying the ability of stem cells to divide and form additional cells? all cells come from preexisting cells. cells are the basic units of structure and function of all living things. all organisms are composed of cells. all cells are similar in composition and metabolic activities.

Explanation:

To solve this, we analyze each option:

• Option "All cells come from preexisting cells": Stem cells dividing to form new cells shows new cells originate from existing stem cells, matching this part of cell theory.
• Option "Cells are the basic units...": This is about cells as structural/functional units, not cell division origin.
• Option "All organisms are composed...": This is about organism - cell composition, not cell division.
• Option "All cells are similar...": This is about cell composition/metabolism similarity, not cell origin from division.

Answer:

A. All cells come from preexisting cells.