When Protein Membrane Receptors Are Activated, What Usually Happens

When protein membrane receptors are activated, what usually happens?

A) A change occurs in intracellular ion concentration.
B) The receptors open and close in response to protein signals.
C) A change occurs on only one membrane surface: exterior or interior.
D) The receptor preferentially binds with lipid or glycolipid signal molecules.
E) The receptor changes conformation after binding with signal polypeptides.