Final answer:
Reform Jews in the 19th century adopted more liberal and modern practices to become less isolated from their non-Jewish communities, embracing individual choice and engagement with modern society.
Step-by-step explanation:
In an effort to become less isolated from their non-Jewish communities, Reform Jews in the 19th century adopted more liberal and modern practices. This move was a response to the changing societal dynamics where Jews in certain European contexts were gaining legal emancipation but still faced various forms of anti-Semitism. Reform Judaism emerged as an innovative branch of Judaism that embraced change, focused on individual choice, and engaged positively with modern culture and society.