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.
