You are presented with the question "What are membranes attached to sites where proteins are made?" and the following answer choices: 
- the body's largest organ
 - Veins and arteries.
 - epidermis and dermis
 - layers of fat
 - cell walls
 - cell membranes
 - endoplasmic reticulum
 - brain cells

Now knowing that ribosomes are sites where proteins are made and endoplasmic reticulum are membranes attached to ribosomes, choose the best answer.


 

       endoplasmic reticulum  