The tubules of which of the following cell organelles carry numerous granule-like structures, the ribosomes?

It is a system of highly branching membranes, which almost fills the space inside the cell membrane. Some of the branches of endoplasmic reticulum are connected to the plasma membrane while some of them are connected to the nuclear membrane. An examination of endoplasmic reticulum under the electron microscope reveals two types of membranes:(i) Smooth endoplasmic reticulum (SER) in which the surface of the tubules lacks granules. (ii) Rough endoplasmic reticulum (RER) in which the surface of the tubules contain numerous granule-like structures called ribosomes.