If You Were to Study Top-Down Processing as It Applies

If you were to study top-down processing as it applies to smell, which of the following topics would be most relevant?

A) Whether people recognize a lemon fragrance more readily when they see a photo of a lemon than when they see a photo of a rose.
B) Whether the chemical structure of lemon-fragrance molecules is substantially different from the chemical structure of rose-fragrance molecules.
C) Whether the receptors in the nasal passages respond differently to lemon and rose fragrances.
D) Whether the brain stores lemon and rose fragrances in different locations.