This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Ribosomes are usually associated with: 
Select and explain. 
A. Endoplasmic reticulum, B. Mitochondria, C. Nucleolus, D. Plasma membrane
A: Endoplasmic reticulum
Answer: A: Endoplasmic reticulum 
Explanation: None