A Molecule That Is Detected by Our Sense of Smell

A molecule that is detected by our sense of smell first binds to

A) special receptor proteins located at the surface of thermoreceptor cells lining the upper nasal cavity.
B) specific receptor proteins on the cilia of receptor cells located in the epithelium of the upper nasal cavity.
C) hairs that extend beyond the mucus layer and line the upper and lower nasal cavities.
D) special mechanoreceptor cells located in the epithelium of the lower nasal cavity.