Biology

The correct answer is: D.Rough ER.

Protein synthesis and folding primarily occur in the rough endoplasmic reticulum (Rough ER), which is studded with ribosomes. These ribosomes are responsible for synthesizing proteins, which are then folded and processed in the rough ER.

Here's a quick rundown of the other options:

A.Smooth ER: Involved in lipid synthesis, detoxification, and calcium ion storage, but not prote...