Answer:
The pair of killers who operated in Canada, with the first known murder victim being the sister to one of them, is 3) Paul Bernardo and Karla Homolka.
Step-by-step explanation:
Paul Bernardo and Karla Homolka were a notorious Canadian couple responsible for a series of heinous crimes in the 1990s. One of their victims was Karla's sister, Tammy Homolka, whose death was initially believed to be accidental. The couple's sadistic acts included the sexual assault and murder of several young women.
Their crimes shocked the nation, and the case unfolded with revelations about the extent of their brutality. Paul Bernardo is serving a life sentence, while Karla Homolka struck a controversial plea deal and served a reduced sentence in exchange for her testimony against Bernardo.
Option 3 is correct.