Final answer:
The largest cultural split in 1920s America was between urban Americans, who embraced modern changes, and rural Americans, who upheld traditional norms. This divide marked the era as one of considerable social change.
Step-by-step explanation:
The largest cultural split in 1920s America was D. Between urban Americans and rural Americans. The era witnessed a drastic transformation where urban centers grew and people moved into cities, embracing modern lifestyles, which contrasted sharply with the traditional norms upheld in rural towns. Significant events such as the Sacco and Vanzetti trial, and the Scopes trial highlighted the tension between these differing values, where urban Americans were often seen as modernist and embracing change, whereas rural Americans were seen as traditionalist and resistant to change. This cultural divide was a defining characteristic of the 1920s, marking it as a period of significant social evolution in American history.