The correct option is B Endoplasmic reticulum
The endoplasmic reticulum is a tube-like structure present in the cell, which extends all over the cell. The Endoplasmic Reticulum facilities transport of materials from one part of the cell to another, thus forming the cell's circulatory system. It has the fluid-filled lumen which almost fills up the intracellular cavity. Hence, ER is involved in providing shape and mechanical support to colloidal cytoplasmic matrix and forming the ultra structural skeletal framework. Therefore, option D is correct.