Answer:
a. cell membrane
c. rough endoplasmic reticulum
Step-by-step explanation:
The cell membrane is also called the plasma membrane, is a thin flexible membrane made of lipoprotein. It is a semi-permeable membrane only allows small and non-polar molecules to pass across and prevents polar ions or molecules to pass. Thus, it controls the movement of molecules and maintaining the constant internal environment.
Endoplasmic reticulum (ER) is a member of the endomembrane system of a cell. When the ribosomes are present on its cytoplasmic surface, it is called rough endoplasmic reticulum (RER). Due to the presence of ribosomes, the reticulum gives texture like sandpaper. The RER provides a platform for the synthesis of polypeptides by ribosomes.