Final answer:
CN I, or the olfactory nerve, is purely sensory and transmits information about smells from the nose to the brainstem.
Step-by-step explanation:
The cranial nerves are responsible for the sensory and motor functions of the head and neck. There are twelve cranial nerves, which are designated CNI through CNXII. While most cranial nerves are a combination of sensory and motor fibers, the olfactory nerve, also known as CN I, is purely sensory. It transmits information about smells from the nose to the brainstem.