Which of the following stomachs is found in horses, rabbits, guinea pigs, and hamsters?

Horses, rabbits, guinea pigs, and hamsters are classified as hindgut-fermenters. This means they have evolved a specialized digestive process that occurs mainly in their large intestines and ceca. These animals possess a single-chambered stomach, which is typical of monogastric animals, but their digestive strategy differs significantly because they rely on fermentation and microbial digestion of fibrous plant materials in the hindgut.

In hindgut fermenters, the fermentation of ingested food occurs after the stomach, allowing for the breakdown of complex carbohydrates and the absorption of nutrients much later in the digestive tract. This adaptation allows these animals to efficiently utilize high-fiber diets, such as grasses and hay, which is essential for their survival in their natural environments.

The correct choice reflects an understanding of this unique digestive process. Ruminants have a multi-chambered stomach, allowing for a different fermentation process, while "digastric" suggests more than two stomach chambers, which does not apply to these animals. Thus, recognizing the concept of hindgut fermentation is key in identifying the correct answer.