Which cranial nerve is responsible for the sense of smell?

The olfactory nerve is specifically responsible for the sense of smell, making it the correct answer. This cranial nerve, known as cranial nerve I, transmits sensory information related to odors from the nasal cavity to the brain. It consists of sensory nerve fibers that detect volatile substances in the air and process these signals to produce the sensation of smell.

In contrast, the optic nerve is involved in vision, transmitting visual information from the retina to the brain. The vestibulocochlear nerve, also known as cranial nerve VIII, is responsible for hearing and balance, conveying auditory information and balance sensations from the inner ear. The trigeminal nerve, cranial nerve V, primarily provides sensation to the face and is also involved in motor functions such as chewing, but it does not play a direct role in the sense of smell. Thus, the olfactory nerve stands out as the only cranial nerve dedicated to the sense of smell.