Interestingly,most Herbivorous Animals Do Not Have the Ability to Digest

Interestingly,most herbivorous animals do not have the ability to digest the cellulose in plants.However,in the absence of this ability,they have evolved a mechanism that allows them to survive despite eating only plant matter,namely

A) converting cellulose to other carbohydrates.
B) avoidance of plants containing cellulose.
C) production of saliva containing amylase.
D) digestion by symbiotic microorganisms.