题目选项分析

In each of the past five years, Barraland's prison population has increased. 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. Clearly, therefore, the percentage of people convicted of crimes who are being given prison sentences is on the increase.

Which of the following, if true, most seriously weakens the argument?

【选项】Barraland has been supervising convicts on parole more closely in recent years, with the result that parole violations have become significantly less frequent.