Here's why:

* Ribosomes are the protein factories of the cell. They read the genetic code carried by messenger RNA (mRNA) and use it to assemble amino acids into protein chains.

* Ribosomes are found in both prokaryotes and eukaryotes. In eukaryotes, they are located in the cytoplasm and attached to the endoplasmic reticulum.

* The process of protein synthesis is called translation. This process involves the ribosome moving along the mRNA, reading the codons (sequences of three nucleotides), and bringing in the corresponding amino acids to build the polypeptide chain.

So, while other cellular components play a role in protein synthesis, the ribosome is the key player, acting as the site where the actual construction of proteins takes place.