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】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.
选项是否正确？