Final answer:
During the 1920s, many Americans who were alarmed by urbanization and the shift away from traditional values began focusing heavily on promoting prohibition to maintain social conservatism.
Step-by-step explanation:
For many Americans, the 1920s were alarming due to urbanization and the shift away from traditional values. The correct answer to the question of what they began focusing heavily on is C) Promoting prohibition. This era, also known as the Roaring Twenties, was characterized by significant social and cultural changes. Urban centers like New York, Chicago, and Philadelphia grew rapidly, signaling a shift towards a more modern, urban culture. Conversely, many Americans, particularly those in rural areas, felt threatened by these changes and responded by embracing social conservatism, which for some included the support of prohibition as a way to try to maintain traditional values and combat the perceived moral decline associated with urban life.
The temperance movement gained momentum in this context, stemming from concerns over new social conditions such as increased urbanization and immigration. Despite the progressive trends of the time, such as the New Woman, jazz music, and a more permissive morality, there remained a significant portion of the population that was resistant to change and deeply concerned about the preservation of conventional norms.