Fact 1: Ribosomes are structures in the cytoplasm where proteins are made.

Fact 2: Endoplasmic reticulum are membranes attached to ribosomes.

Given the two facts above, answer the question "Endoplasmic reticulum are what attached to structures in the cytoplasm where proteins are made?" with the following options: 
- recycling
 - allow growth
 - membranes
 - organ
 - layers of fat
 - more abundant
 - epidermal
 - Most plants


 

   membranes      