The correct answer is option 3, Smelling. Jacobson`s organ, also known as the vomeronasal organ, is a sensory organ found in many animals including snakes, lizards, and some mammals. It is primarily associated with the sense of smell. This organ helps animals detect pheromones, which are chemical signals released by other animals. By detecting these pheromones, animals can gather important information about the reproductive status, social hierarchy, and territory of other individuals. Unlike the regular olfactory system, which detects airborne odor molecules, Jacobson`s organ is specialized in detecting pheromones that are often found in bodily secretions or marking substances. Therefore, option 3, Smelling, is the correct choice as Jacobson`s organ is directly related to the sense of smell in animals.