The correct option is D Fat and protein synthesising cells
The endoplasmic reticulum is a network of membranous sacs like structure, such as cisterns, vesicles, and narrow tubules. On the basis of presence or absence of ribosomes on it's surface, these are two types-
Rough endoplasmic reticulum (RER) with ribosomes on it's surface prominently sites where the protein is synthesizing.Smooth endoplasmic reticulum (SER) lack ribosomes and the sites for synthesis of cholesterol and lipids. Thus the correct answer is option D.