請回答下列21題至第25題
Humans are a fundamentally social species. They are unable to reproduce and    21    to reproductive age
without a group. They lack natural    22    such as slashing canines, bodily armor, or fleetness of foot； they have an extended infancy    23    by years of further development before they reach reproductive maturity. Many of the evolved characteristics that have    24    humans to adapt to a wide range of physical environments, such as tool making and feeding on both animals and plants, and create dependence on collective knowledge and cooperative information sharing    25    individuals and between generations. Humans are, indeed, an obligately interdependent species.
【題組】21
(A) surpass
(B) survive
(C) surge
(D) suspend