Answer :
The correct answer is 4) An endoplasmic reticulum
Explanation:
Prokaryotic cells different from eukaryotic ones do not have a defined nucleus or bounded organelles such as the mitochondria, Golgi apparatus, and endoplasmic reticulum. In the case of the endoplasmic reticulum, this is an organelle related to synthesis, folding and transport of proteins that can be found in most eukaryotic cells but not in prokaryotic cells. Additionally, both prokaryotic and eukaryotic cells contain a cell wall, DNA and ribosomes as these structures are essential for life functions such as protection, reproduction, etc. According to this, the one that is not part of a prokaryotic cell is the endoplasmic reticulum.