This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
Prokaryotes have all, except 
Select and explain. 
A. Rigid cell wall, B. Flagella, C. Ribosomes, D. Well defined Nuclear membrane
D: Well defined Nuclear membrane
Answer: D: Well defined Nuclear membrane 
Explanation: Prokaryotic cells have Cell wall, Cell membrane, ribosome, Nucleoid. BUT Nuclear membrane, nucleolus, endoplasmic reticulum, mitochondria are absent Ref: Ananthanarayana textbook of Microbiology 9th edition Pgno : 9