Who killed the three chickens（）

A．Some of their prisoners are allowed to study or work outside prisons.
B．Most of their prisoners are expected to work.
C．Their prisoners are often sent to special centers for skill training.
D．Their prisoners are allowed freedom to visit their families.

A．Because they have a driving license.
B．Because they have received special training.
C．Because the traffic conditions in London are good.
D．Because the traffic system of the city is not very complex.