A) are large cytoplasmic assemblies made of several ribosomes each translating their exclusive mRNA. B) are only found in the eukaryotic cytoplasm. C) can take advantage of the circularization of eukaryotic mRNA (by interactions between the 5' and 3' ends of the mRNA) to further speed up the rate of protein synthesis. D) are mostly translationally inactive and are normally used by the cell to store the ribosomes and their associated mRNAs for future use. E) All of the above.