Herbivores are plant eating animals. Plants have cellulose that need an enzyme called cellulase for its digestion. Herbivores lodge have a microbial flora are obligate or facultative anaerobes that can decompose complex plant material, such as cellulose, hemicellulose, starch, and proteins. The hydrolysis of cellulose results in sugars, which are further fermented to acetate, lactate, propionate, butyrate, carbon dioxide, and methane.
So, the correct answer is 'Herbivores'.