C is correct.
A. Not being able to take college-level courses while in prison is unlikely to deter anyone from a crime that he or she might otherwise have committed. --> Not as strong as choice C
B. Former inmates are no more likely to commit crimes than are members of the general population. --> great, but this doesn't help us
C. The group of inmates who chose to take college-level courses were not already less likely than other inmates to commit crimes after being released. --> CORRECT;
...
A. Not being able to take college-level courses while in prison is unlikely to deter anyone from a crime that he or she might otherwise have committed. --> Not as strong as choice C
B. Former inmates are no more likely to commit crimes than are members of the general population. --> great, but this doesn't help us
C. The group of inmates who chose to take college-level courses were not already less likely than other inmates to commit crimes after being released. --> CORRECT;
...




