People in the 18th and 19th centuries used to sleep about 9.5 hours a night because they had ______.

A．sleep is the first thing that can be sacrificed when one is busy
B．they need more sleep to cope with the complexities of everyday life
C．to sleep is something one can do at any time of the day
D．enough sleep promotes people's drive and ambition

A．believes the reform has reduced the government's burden
B．insists that welfare reform is doing little good for the poor
C．is over-enthusiastic about the success of welfare reform
D．considers welfare reform to be fundamentally successful