Which group of dogs is mentioned as part of the crossbreeding that developed the Rat Terrier in the late 19th/early 20th centuries?
Answer
English White Terrier and Fox Terrier
The breed was developed from crosses including the English White Terrier, Fox Terrier, and possibly some small sight hounds.

Related Questions
What was the original primary utility role for which Rat Terriers were developed on American farms?What is specified as a crucial component for keeping a Rat Terrier content daily, beyond just long walks?Which of these performance sports is mentioned as an activity where Rat Terriers generally excel?How do Rat Terriers typically behave around people they are not familiar with initially?What training method is advised as yielding the best results for the intelligent but stubborn Rat Terrier?Why must introductions to small household pets like guinea pigs be managed with extreme caution?If a Rat Terrier is under-exercised, what behaviors might they engage in to find their own entertainment?What characteristic common to terriers do Rat Terriers possess despite their small size (ten to twenty-five pounds)?What specific security measure is suggested for fencing to thwart a Rat Terrier's attempts at digging out?Which group of dogs is mentioned as part of the crossbreeding that developed the Rat Terrier in the late 19th/early 20th centuries?How are Rat Terriers generally described regarding their tendency to bark as watchdogs?