Final answer:
Gabrielle "Coco" Chanel was responsible for introducing trousers and sportswear for daily use in the 1920s, revolutionizing women's fashion and contributing to societal change.
Step-by-step explanation:
The individual who introduced trousers and sportswear for daily use in the 1920s was Gabrielle "Coco" Chanel. Coco Chanel was a pioneering French fashion designer whose innovative approach to women's fashion was instrumental in popularizing a more relaxed, casual style, at a time when women's fashion was largely restrictive and dominated by corsets and elaborate gowns. She believed that women needed to be comfortable to be stylish, and thus introduced trousers and sportswear as a chic, everyday option. Her influence extended beyond simply fashion; it marked a change in the social norms regarding women's clothing and contributed to the evolution of women's roles in society.