The flying fox is not a fox at all. It is an extra large bat that has got a fox's head, and that feeds on fruit. Like all bats, flying foxes hang themselves by their toes   when at rest, and travel in great crowds when out flying. A group will live in one place for years. Sometimes several hundreds of them occupy a single tree. As they return to the tree towards sunrise, they quarrel among themselves and fight for the best places until long after daylight. Flying foxes have babies once a year, giving birth to only one at a time. At first the mother has to carry the baby on her chest wherever she goes. Later she leaves it hanging up, and brings back food for it to eat. Sometimes a baby bat falls to the ground. Then the older ones fly down and try to pick it up. If they fail to do so, it will die. Often hundreds of baby bats can be found lying on the ground at the foot of the tree. The passage tells us that there is no difference between the flying fox and the ordinary bat in   _  .
their size their appearance the kind of food they eat the way they rest
Question: The flying fox is not a fox at all. It is an extra large bat that has got a fox's head, and that feeds on fruit. Like all bats, flying foxes hang themselves by their toes   when at rest, and travel in great crowds when out flying. A group will live in one place for years. Sometimes several hundreds of them occupy a single tree. As they return to the tree towards sunrise, they quarrel among themselves and fight for the best places until long after daylight. Flying foxes have babies once a year, giving birth to only one at a time. At first the mother has to carry the baby on her chest wherever she goes. Later she leaves it hanging up, and brings back food for it to eat. Sometimes a baby bat falls to the ground. Then the older ones fly down and try to pick it up. If they fail to do so, it will die. Often hundreds of baby bats can be found lying on the ground at the foot of the tree. The passage tells us that there is no difference between the flying fox and the ordinary bat in   _  .
A. their size
B. their appearance
C. the kind of food they eat
D. the way they rest
Answer: