Final answer:
Harry Gordon Selfridge broke conventional norms when he opened his department store off Oxford Street by introducing innovative practices that transformed the retail landscape.
Step-by-step explanation:
Harry Gordon Selfridge was a pioneer in breaking conventional norms when he opened his department store just off Oxford Street. He incorporated changes that transformed the retail landscape. Selfridge introduced several innovative practices, including fixed prices, wide variety of goods, and the use of advertising to promote his store. He also focused on creating an enticing shopping experience for customers through enticing window displays and elegant store interiors. By implementing these changes, Selfridge revolutionized the retail industry and set new standards for department stores.