In which cellular organelle does translation occur?

Translation is the process by which ribosomes synthesize proteins from messenger RNA (mRNA). Ribosomes serve as the machinery for reading the mRNA sequence and assembling the corresponding amino acids into a polypeptide chain, which eventually folds into a functional protein. This process occurs in both prokaryotic and eukaryotic cells and is critical for gene expression.

While the nucleus, mitochondria, and chloroplasts have their own roles in cellular function and also contain some aspects of protein synthesis, it is the ribosome that is specifically responsible for the translation process. The nucleus is primarily involved in transcription, where DNA is converted into mRNA. Mitochondria and chloroplasts have their machinery for translation related to their own genomes, but generally, ribosomes are the central organelles for the translation that occurs in the cytoplasm of eukaryotic cells and in the cytosol of prokaryotes. This distinguishes ribosomes as the correct answer in the context of the question.