The correct answer is option 4, Ribosomes. Protein synthesis, which is the process of creating proteins, takes place in the ribosomes. Ribosomes are small organelles found in all cells, both prokaryotic and eukaryotic. They are responsible for translating the genetic information stored in DNA into functional proteins.

Option 1, Golgi bodies, are another organelle found in cells. Golgi bodies are involved in processing, packaging, and transporting proteins within the cell. They receive proteins from the endoplasmic reticulum and modify them before they are sent to their proper destinations. However, Golgi bodies are not directly involved in protein synthesis.

Option 2, Mitochondria, are known as the "powerhouses" of the cell and are responsible for generating energy in the form of ATP. While mitochondria do contain their own set of ribosomes, protein synthesis primarily occurs in the ribosomes outside of the mitochondria.

Option 3, Plastids, are organelles found in plants and some algae. They have various functions, including photosynthesis and storing pigments. Plastids do not play a direct role in protein synthesis.

Therefore, the correct answer is option 4, Ribosomes.