Which of the following statements are true of cell membranes? (Read carefully and select all of the correct statements.)

A)Cholesterol provides stability.
B)Receptor sites are made of glucose.
C)A cell membrane is selectively permeable.
D)Phospholipids are not always present.
E)Microvilli are cell membrane folds that sweep materials across the cell surface
F)Receptor sites are part of cell communication.