Cattle are able to survive on a diet consisting almost entirely of plant material because
A) they are autotrophic. B) cattle, like rabbits, re-ingest their feces. C) they manufacture all 15 amino acids out of sugars in the liver. D) cattle saliva has enzymes capable of digesting cellulose. E) they have cellulose-digesting, symbiotic microorganisms in chambers of their stomachs.