Extranuclear DNA is found in

The correct option is Chloroplast.

Step-by-step Explanation:
1. Concept of Extranuclear DNA: In eukaryotic cells, the vast majority of genetic material is enclosed within the nucleus. However, DNA that is located outside the nucleus in the cytoplasm is referred to as extranuclear or cytoplasmic DNA.
2. Origin and Organelles: According to the endosymbiotic theory, certain organelles originated as free-living prokaryotic cells that entered into a symbiotic relationship inside a host eukaryotic cell. As a result, these organelles have retained their own genomes. In plants and algae, the two organelles that possess their own DNA are mitochondria and chloroplasts.
3. Evaluating the Options:
- Ribosome: These structures are composed of RNA and proteins, serving as the site of protein translation. They do not contain DNA.
- Golgi apparatus: This membrane-bound organelle is involved in trafficking, processing, and packaging proteins. It does not contain DNA.
- Chloroplast: These double-membraned organelles carry out photosynthesis. They contain their own circular DNA (chloroplast DNA), which allows them to replicate and synthesize some of their own proteins independently of the nucleus.
- Endoplasmic reticulum: This organelle is a network of membranes involved in lipid and protein synthesis, and it lacks its own DNA.
4. Conclusion: Consequently, extranuclear DNA is located within the chloroplast.