What characteristic identifies the horse as a nonruminant herbivore?

The characteristic that identifies the horse as a nonruminant herbivore is the presence of a large cecum to digest fiber. Horses are classified as nonruminant herbivores because they have a single-chambered stomach, similar to humans, but their digestive systems are particularly adapted for breaking down fibrous plant materials through fermentation. The cecum, a large pouch located at the beginning of the large intestine, plays a critical role in this process.

In horses, the cecum houses a diverse population of microorganisms that effectively break down cellulose and other complex carbohydrates found in plant materials. This adaptation allows horses to extract nutrients from fibrous forage, such as grasses, making it essential for their digestive efficiency. As they graze and consume forage, the fermentation processes in the cecum enable horses to gain the necessary energy and nutrients from their largely plant-based diets.

The other options do not accurately describe the key characteristics associated with nonruminant herbivores. For instance, the ability to regurgitate food is a feature of ruminant animals like cows and sheep, which have multiple stomach chambers that allow for this behavior. The presence of multiple stomach chambers is also a defining trait of ruminants, which is