What does the horse's olfactory sense refer to?

The horse's olfactory sense refers to its ability to detect and differentiate smells, which is represented by the correct answer. Horses have a highly developed sense of smell that plays a crucial role in their communication and social interactions. This olfactory capability allows them to recognize other horses, potential predators, and food sources, making it an essential aspect of their survival and well-being.

In contrast, the other senses mentioned in the incorrect options pertain to different modalities. Hearing relates to the horse's auditory capabilities, sight pertains to vision, and touch involves physical sensation. Each of these senses contributes to a horse's overall perception of the environment, but it is the olfactory sense that specifically deals with their ability to perceive odors. Understanding this can help in various training and management decisions, as a horse's behavior can often be influenced by what it smells in its surroundings.