Final answer:
Rough Endoplasmic Reticulum (ER) has ribosomes attached to its surface, making it the primary site of protein production.
Step-by-step explanation:
Rough Endoplasmic Reticulum (ER) has ribosomes attached to its cytoplasmic surface, giving it a studded or bumpy appearance. These ribosomes are responsible for protein synthesis, making the rough ER the primary site of protein production. Proteins synthesized within the ribosomes are released into the rough ER and can undergo modifications before being transported to other cellular destinations.