The correct option is B Endoplasmic Reticulum
Endoskeleton refers to the internal membrane system of a cell. The internal membrane system supports the cells like a skeletal system supports the body of an organism. The endomembrane system comprises of endoplasmic reticulum, Golgi apparatus, lysosome, and plasma membrane. Membranes of ER may bear ribosomes, then ER is called granular or rough endoplasmic reticulum (RER). It is abundant in cells engaged in active secretion and protein synthesis. Endoplasmic reticulum without ribosomes is called as smooth endoplasmic reticulum (SER). SER occurs in cells engaged in producing a lot of lipids. SER also takes part in the synthesis of vitamins, carbohydrates and detoxification. Thus, the correct answer is option A.