During mitosis, the genetic material in a cell is replicated, and then the cell splits into two new cells. The two new cells are genetically identical to the original cell.

Which part of cell theory do these statements best support?
A.
New cells can be spontaneously generated.
B.
All cells come from pre-existing cells.
C.
Both living and nonliving substances are made of cells.
D.
All organisms are made up of many different types of cells.