Which type of digestive system is characterized by a simple stomach?

The monogastric digestive system is characterized by having a simple stomach, which means that it consists of a single-chambered stomach. This type of digestive system is commonly found in animals such as pigs, humans, and dogs, where the digestion process primarily occurs in one main stomach, followed by the small and large intestines. The design allows for efficient digestion of grains and other starches, as these animals have adaptations to break down complex carbohydrates effectively.

In contrast, ruminants possess a more complex digestive system with multiple stomach chambers, allowing them to digest fibrous plant material more efficiently through a process called rumination. Multigastric systems are similar to ruminants but can include variations, whereas the term "omnivorous" relates to a dietary classification rather than a specific type of digestive anatomy. Therefore, the distinguishing feature of having a simple stomach makes monogastric the correct choice for this question.