In 1838, matthias schleiden published his observation that plant tissues are composed of cells. a year later, theodor schwann published evidence that animal tissues were composed of cells. which part of the cell theory is directly supported by the work of schleiden and schwann? (2 points)

a. all living things are made of cells.

b. cells are the basic structural and functional units of life.

c. all cells come from other preexisting cells.

d. cells form through spontaneous generation.
i chose letter c.