Ribosomes are sites where proteins are made, and endoplasmic reticulum are membranes attached to ribosomes. Given these facts, what are membranes attached to sites where proteins are made among the following options:
- the body's largest organ
 - Veins and arteries.
 - epidermis and dermis
 - layers of fat
 - cell walls
 - cell membranes
 - endoplasmic reticulum
 - brain cells


 

       endoplasmic reticulum  