* Cytoplasm: This is the gel-like substance that fills the cell. Ribosomes float freely in the cytoplasm, where they synthesize proteins that are needed within the cell itself.

* Rough Endoplasmic Reticulum (RER): This is a network of membranes within the cell. Ribosomes attach to the RER, where they synthesize proteins that are destined for export outside the cell or for use in other organelles.

So, the answer depends on what you're looking for. If you're asking where you *find* ribosomes in general, then the answer is both the cytoplasm and the RER. If you're asking where ribosomes are *located* when they're making proteins for specific purposes, then the answer is either the cytoplasm or the RER.