Which nerve is responsible for the sense of smell in horses?

The olfactory nerve is crucial for the sense of smell in horses, just as it is in many other animals, including humans. This nerve is specifically designed to carry sensory information from the nasal cavity to the brain, making it essential for detecting odors. In horses, a keen sense of smell plays a vital role in their behavior, social interactions, and environmental awareness, aiding in locating food, other animals, and detecting potential dangers.

The optic nerve is primarily responsible for vision, conveying visual information from the retina to the brain, and does not play a role in the detection of smells. The trigeminal nerve is associated with sensation in the face and motor functions such as biting and chewing, but it does not convey sensory information related to the sense of smell. The facial nerve is involved in controlling facial expressions and transmitting taste sensations but is also not linked to the olfactory system. Thus, the olfactory nerve is the specific nerve dedicated to the sense of smell, making it the correct choice for this question.