Which term describes an extensive network of tubes, sacs, and vesicles throughout a cell that provides transport as its main function?

The endoplasmic reticulum is the term which describes an extensive network of tubes, sacs, and vesicles throughout a cell that provides transport as its main function. The endoplasmic reticulum is a small organelle and is found in most Eukaryotic cells. It is not found in red blood cells. The endoplasmic reticulum is a network in the core of the cell and occurs within the nuclear membrane and is involved in the synthesis of lipids and proteins. The endoplasmic reticulum also usually has ribosomes attached to it. 

The correct answer is c

I’m not exactly sure what your trying to ask, but if it’s how an organelle is similar to a body system or a part a nucleus is like a in function. but i don’t fully understand what you’re trying to ask