Final answer:
In nonruminant herbivores such as horses, fermentation takes place in the cecum, a part of the large intestine, where microorganisms break down plant material.
Step-by-step explanation:
In nonruminant herbivores, such as horses, fermentation occurs in the cecum. This is a pouched organ at the beginning of the large intestine. Unlike ruminants like goats and cows, which have a four-chambered stomach (rumen, reticulum, omasum, abomasum) for fermentation and digestion of plant material, nonruminant herbivores rely on their cecum for the fermentation process. In the cecum, microorganisms break down cellulose and other complex carbohydrates from plant material, which cannot be digested by the animal's own enzymes. Therefore, the correct answer is b) Cecum.