Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: 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 . Answer: rough & smooth
What are the two types of endoplasmic reticulum?