The answer is <span>A. presence of cell membranes.
A classification of living things can be based on many different characteristics but a presence of cell membranes is not one of them. <u>ALL living things have cell membranes.</u> So, <u>there could be no classification</u> of organisms with cell membranes and organisms without cell membranes. On the other hands, based on mode of nutrition, organisms can be classified of autotrophs and heterotrophs. Based on presence of nucleus, organisms can be prokaryotes (without a nucleus) and eukaryotes (with the nucleus). Number of cells is base for classification of living things on unicellular and multicellular.</span>
