Which of the following is NOT an organelle found in prokaryotic cells?

Prokaryotic cells are characterized by their simpler structure compared to eukaryotic cells, and one of the defining features is the absence of membrane-bound organelles. In prokaryotic cells, there is no nucleus; instead, genetic material is located in a region called the nucleoid, which is not enclosed by a membrane. This is a fundamental difference that distinguishes prokaryotic cells from eukaryotic cells, which have a true nucleus.

The other options listed, such as the cell wall, capsule, and ribosomes, are indeed structures found within prokaryotic cells. The cell wall provides structural support and protection, while capsules can offer additional protection and assist in adhering to surfaces. Ribosomes, although not organelles in the membrane-bound sense, are essential for protein synthesis and are present in both prokaryotic and eukaryotic cells.

Thus, the presence of a nucleus in eukaryotic cells versus its absence in prokaryotic cells is what makes the first choice the correct answer to the question of which structure is not found in prokaryotic cells.