Which of These Statements Is Generally True of Integral Membrane $\alpha$

Which of these statements is generally true of integral membrane proteins?

A) The secondary structure in the transmembrane region consists solely of $\alpha$ -helices or $\beta$ -sheets.
B) The domains that protrude on the cytoplasmic face of the plasma membrane nearly always have covalently attached oligosaccharides.
C) They are unusually susceptible to degradation by trypsin.
D) They can be removed from the membrane with high salt or mild denaturing agents.
E) They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer.