Which cranial nerve is evaluated using the "smell test"?

The olfactory nerve, which is cranial nerve I, is responsible for the sense of smell. It is the nerve evaluated using the "smell test" because this test involves identifying various scents, which assesses the function of the olfactory nerve. During the evaluation, a person is typically asked to close their eyes and plug their nostrils, and then they are presented with different odors to detect. This allows a clinician to determine if the olfactory nerve is functioning properly.

The other options correspond to different sensory and motor functions. The optic nerve is primarily concerned with vision; the vestibulocochlear nerve is related to hearing and balance; and the facial nerve controls muscles of facial expression and has some sensory functions related to taste. Therefore, the olfactory nerve is the only option associated specifically with the sense of smell, making it the correct choice for this question.