Final answer:
The correct answer is (a) roles. The changing roles of men and women in the marketplace over the past 30 years highlight a significant cultural evolution in the United States, marked by increased female participation in economic activities and a shift in traditional gender dynamics.
Step-by-step explanation:
The changing attitudes and roles of men and women in the marketplace is one of the most notable cultural changes in the United States in the past 30 years. This phenomenon is rooted in the historical progression of gender dynamics and economic activities. Since the 19th century, where an agrarian producer culture prevailed, there has been a significant shift towards more transient urban cultures. Here, women have increasingly entered the public sphere, particularly in consumer markets.
By the 1920s, shopping had evolved into a task predominantly performed by women, representing a cultural transformation from it being a masculine venture. The economic empowerment of women through education and commercial opportunities further altered traditional gender roles, challenging the 'money mentality' and creating a context where gender became a more differentiated factor than social class or rank.
Despite the enduring adherence to traditional gender roles in some professional fields, there has been a broader shift in public opinion on gender-related issues, as seen in the diversification of employment and political influence among women. This demonstrates the significant evolution of cultural values and attitudes to work, with impacts across various aspects of society, including technology, sexuality, and public opinion on social issues.