One Factor That Makes It Possible for the Odorant Receptors

One factor that makes it possible for the odorant receptors on the antennae of moths to be extremely sensitive is that

A) each receptor is specific for only one odor.
B) each receptor can respond to many different odors.
C) each antenna has only a few receptors and each is specific.
D) moths only need to recognize one odor,and all receptors respond to it.
E) moths are very small,so they require few odorant receptors to be effective.