Synthesis of ribosomes in prokaryotes occurs in

The correct option is cytosol.

To understand why this is correct, we can break down the differences in cellular structure between prokaryotes and eukaryotes:
1. Prokaryotic Cell Structure: Prokaryotes (such as bacteria and archaea) are unicellular organisms that lack a defined, membrane-bound nucleus and other membrane-bound organelles. Their genetic material is located in an irregularly shaped region called the nucleoid, which is in direct contact with the cytoplasm.
2. Eukaryotic Cell Structure: Eukaryotes (such as plants, animals, and fungi) possess a membrane-bound nucleus. Within the nucleus is a specialized substructure called the nucleolus, which is the site of ribosome synthesis and assembly in eukaryotic cells.
3. Ribosome Synthesis: Ribosomes are cellular machines responsible for protein synthesis and are composed of ribosomal RNA (rRNA) and proteins. Since prokaryotes do not have a nucleus, nucleolus, or nucleoplasm, all cellular processes—including transcription, translation, and the assembly/synthesis of ribosomes—must take place within the single open compartment of the cell, which is the cytosol (cytoplasm).

Therefore, while ribosome synthesis occurs in the nucleolus in eukaryotes, it occurs in the cytosol in prokaryotic cells.