I see why E is correct but why is D wrong?

Hi @capoleway@gmail.com, Happy to help! We learn that, in the last year, the city experienced a 15% decrease in the rate of violent crime. The police commissioner concludes that the drop in violent crime must have been due to the new mandatory sentencing law. Why? Because no other major policy changes were made and the mandatory sentencing law requires that all violent criminals serve time in prison, thereby disincentivizing the commission of violent crimes. Answer choice (D) is incorrect because one would expect the rate of violent crime to go up if the definition of violent crime was broadened. This does not impact the police commissioner's conclusion that the decrease in violent crime was the result of the new sentencing law. Hope this helps! Please let us know if you have any further questions.