Concept:Herbivores differ in digestive systems based on whether they are ruminant or non-ruminant.Explanation:Statement I is true because non-ruminant herbivores have a long caecum that helps digest cellulose.Statement II is false because non-ruminant herbivores have a simple stomach; only ruminant herbivores have a complex, multi-chambered stomach.Statement III is true because ruminant herbivores chew the cud as part of rumination.Thus, the true statements are I and III only.Answer:B. I and III only