Answer:
D. All cells must have a nucleus
Explanation:
According to the tenets of the cell theory:
a. the cell is the structural unit of life, in other words without the cell there is no life;
b. Reproduction cannot occurs without cell division, hence cells can only arise by division from a preexisting cell;
c. All organisms are composed of one or more cells, prokaryotes are referred to as singled celled organisms while eukaryotes are referred to as multi-cellular organisms;
d. Not all cells must have a nucleus. There are two major types of cells; the prokaryotic cells and the eukaryotic cells. Eukaryotic cells have a well defined nucleus and other membrane bound organelles, while prokaryotic cells do not have a defined nucleus and other membrane bound organelles. Notwithstanding, they both contain genetic materials.
