Read the following article and answer the question. Article: Koalas are found only in prefix = st1 /Australia. Even if called koala bear, this animal has nothing to do with the actual bear; it is not even a mammal , but a marsupial , like the kangaroo. Its closest living s are the wombats . A koala is about 60-80cm long and weighs 5-14kg. The name "koala" means "no drink", and refers to the koala's ability to go for days without water. Koalas get the water content they need from the eucalyptus leaves on which they feed. The koala is the only mammal with a digestive system that can feed only on eucalyptus leaves--incidentally, these leaves are highly poisonous if eaten by humans. One individual consumes about 5kg of eucalyptus leaves daily and it may never drink water! The koala is a _ mammal. They prefer to move around just after sunset, spending daytime sleeping in the fork of a tree. A koala spends sleeping 75% of its time. The eucalyptus leaves they eat are rich in fiber and poor in proteins and fats. The adult must detoxify leaves with energy expense, while fiber is hard to break down. Because of this poor diet, koalas save energy by sleeping most of the day, while their movements are very slow. Koalas only have one young per year. In summer, baby koalas are born about a month after mating. The female takes it with her mouth and places it into her poach. In 6 months, the young can get out and feed on leaves. There are probably around 2,000 to 8,000 wild koalas in Australiaat present. The extremely fine gray fur is the reason why koala has been heavily hunted in the past. Koalas are killed every year by dogs, cats, dingoes, eagles and owls. They also die of disease and accidents. Question: Koalas do not get poisoned when eating eucalyptus simply because of their _ . Answer:
Possible answers:
(A). special need
(B). living habitat
(C). digestive system
(D). born laziness
(C).