Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
There are two types of endoplasmic reticulum. They are called rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). Both types are shown in Figure below .


Question: What are the two types of endoplasmic reticulum?
rough & smooth
Rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).