Answer:
The answer is rough endoplasmic reticulum.
Step-by-step explanation:
If we apply this analogy to the cellular structures, the type of conveyor belt explained in the question represents the rough endoplasmic reticulum. Because it has a complex structure made up of membrane and ribosomes and it produces only a limited number of proteins just like the very efficient conveyor belt that produces only a few products.
I hope this answer helps.