The answer is B both are unicellular.
E. coli and paramecium are both unicellular. And that is their only common characteristic. E. coli is a prokaryotic unicellular organism while paramecium is a eukaryotic unicellular organism. So, paramecium has nucleus and E.coli has a nucleoid. Neither of them produce essential vitamins. Contractive vacuoles are present only in paramecium.
