Read the following passage and answer the question by choosing among the four alternatives given:
The year was 1888, and the streets of London were plagued by a series of gruesome murders. The infamous killer, Jack the Ripper, struck fear into the hearts of the city's residents as he preyed upon vulnerable women in the dimly lit alleys of Whitechapel. The murders were characterized by their brutality, with the victims being mutilated in a manner that suggested a deep-seated rage and a twisted sense of pleasure for the perpetrator. Despite the efforts of Scotland Yard and a fervent public outcry, Jack the Ripper managed to elude capture, leaving behind a trail of unsolved mysteries and countless theories about his true identity. Over the years, numerous suspects have emerged, ranging from ordinary citizens to prominent figures in society. The case has fascinated criminologists, historians, and amateur sleuths alike, who have tirelessly analyzed the available evidence, examined witness testimonies, and delved into the historical context of the time. Even to this day, the identity of Jack the Ripper remains one of the most enigmatic and perplexing mysteries in criminal history. Who was the man behind the grisly crimes? What drove him to commit such heinous acts? Will we ever uncover the truth behind Jack the Ripper's reign of terror?
Why is the case of Jack the Ripper considered one of the most perplexing mysteries in criminal history?