Among the Model Genetic Organisms, Escherichia Coli, a Single-Celled Bacterium

Among the model genetic organisms, Escherichia coli, a single-celled bacterium, is a prokaryote; saccharomyces cerevisiae, one-celled yeast, is a eukaryote, as are Caenorhabditis elegans, a multicellular nematode worm, and Arabidopisis thaliana, a multicellular plant. Which of these organisms would NOT contain membrane-bound organelles?

A) Escherichia coli
B) Saccharomyces cerevisiae
C) Escherichia coli and Saccharomyces cerevisiae
D) Caenorhabditis elegans
E) Caenorhabditis elegans and Arabidopisis thaliana