Which of the following is not one of the horse's primary senses?

The correct answer highlights that "math" is not one of the horse's primary senses. Horses possess several well-developed senses that are crucial for their survival and interaction with their environment.

Taste, hearing, and smell are all essential senses for horses, allowing them to perceive and react to various stimuli. Their sense of taste helps them distinguish between different types of forage, which is important for their diet and health. Hearing enables them to detect sounds from far away, which can be indicative of potential threats or the presence of other animals or humans. The sense of smell is highly developed in horses and plays a vital role in their social interactions, allowing them to recognize other horses and assess their surroundings.

In contrast, "math" does not relate to any biological function or sensory perception in horses. While horses may be able to respond to certain patterns or routines through training, the concept of understanding mathematical principles does not apply to their capabilities. Therefore, it's clear that the only option that does not pertain to a primary sensory ability of a horse is "math."