This is a good weaken question:
C1: In each of the past five years, Barraland's prison population has increased.
P1: Yet, according to official government statistics, for none of those years has there been either an increase in the number of criminal cases brought to trial, or an increase in the rate at which convictions have been obtained
Conclusion: the percentage of people convicted of crimes who are being given prison sentences is on the increase.
We need to find the statement what will weaken the conclusion which claims that % of people convicted of crimes is on increase.
Lets look at the answer choices:
A. In Barraland the range of punishments that can be imposed instead of a prison sentence is wide.
This does not directly deal with or tell us why the % of people convicted of crimes is on the rise. It deals with prisons, but does not directly deal with the conclusion. So not it.
B. Over the last ten years, overcrowding in the prisons of Barraland has essentially been eliminated as a result of an ambitious program of prison construction.
Out of scope. Overcrowding is not mentioned in the passage and does not deal with the conclusion
C. Ten years ago, Barraland reformed its criminal justice system, imposing longer minimum sentences for those crimes for which a prison sentence had long been mandatory.
Now this is a good choice which claims that something that started 10 years ago is a result for more attendance in prison. It clearly states that the % of people in prison is increasing, not because of people convicted of crimes, but because of something (imposing longer minimum sentence for those crimes for which a prison sentence had long been mandatory) that started 10 years ago. This weakens the conclusion and is the correct answer!
D. Barraland has been supervising convicts on parole more closely in recent years, with the result that parole violations have become significantly less frequent.
Parole deals with people already out of prison and is out of scope, Not it
E. The number of people in Barraland who feel that crime is on the increase is significantly greater now than it was five years ago.
It does not matter how many people 'feel' that crime is on the increase. Does not relate to our conclusion. Too broad to be the correct answer.
Correct answer: C
Hope this helps!
Kudos if I helped