Which one of the following organelle is not found in prokaryotic cells?
Prokaryotic cells do not have a well-organised nucleus. The genetic material is a single molecule of DNA lying in the cytoplasm. Cell organelles like mitochondria, lysosomes, endoplasmic reticulum, chloroplast, nucleolus, etc. are not present in prokaryotic cells.
Examples: Bacteria and blue-green algae.
The correct option is B.