A recent research study of a particular state’s prison systems indicates that prisoners participating in the weekend furlough program are less likely to become repeat offenders after they are released than prisoners who do not participate in the program. The study confirms the researchers’ hypothesis that weekend furlough programs at the state’s prisons are an effective means of reducing crime.
Which of the following, if true, would cast the most serious doubt on the hypothesis to which the last sentence above refers?
(A) The furlough program was available only to prisoners who had demonstrated good behavior while in prison.
(B) The crime rate in other states with similar furlough programs is lower overall than the crime rate in states without furlough programs.
(C) Whether the weekend furlough program is effective depends on how greatly one values the reform of any one prisoner.
(D) Less than half of the prisoners not involved in the furlough program become repeat offenders after they are released.
(E) Less than half of all the prisoners studied participated in the furlough program.