The membrane is selectively permeable because substances do not cross it indiscriminately. Some molecules, such as hydrocarbons and oxygen can cross the membrane. Many large molecules (such as glucose and other sugars) cannot. Water can pass through between the lipids. Ions such as H+ or Na+ cannot.
So I think the answer is D) It lets certain Substances pass through but not others.
It may be either Disagreements or Intractable Situations. I'm not completely sure, sorry. I'd wait for another to come answer your question just to be safe.
